Method of controlling a treatment process and vacuum treatment apparatus

ABSTRACT

A vacuum treatment apparatus eliminate arcing in a vacuum recipient for containing an atmosphere and having a mechanism for generating electrical charge carriers in the atmosphere. A workpiece carrier arrangement and at least two electro-conductive surfaces are in the recipient and a generator unit having an output is connected to the electro-conductive surfaces. The generator includes a DC generator with an output, and a controlled adjusting unit with an input connected to the output of the DC generator. The controlled adjusting unit generates a first output signal in dependency on an output signal of the DC generator during first timespans, and a second output signal during second timespans. The unit may also have a time-controlled discharge or charge current loop connected from one of the electro-conductive surfaces to the other, with a higher ohmic resistance during the first timespans and a lower ohmic resistance during the second timespans.

This application is a continuation, of application Ser. No. 08/641,707,abandoned filed May 2, 1996, which is a continuation of application Ser.No. 08/300,865, abandoned filed Sep. 2, 1994, which is a continuation,of application Ser. No. 08/020,672, filed Feb. 22, 1993, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to a method of controlling a treatmentprocess for an object in a vacuum atmosphere containing electricalchargecarriers and to a vacuum treatment apparatus. More specificallythe invention is directed to such a method or apparatus wherein at leasttwo surfaces of electro-conductive material are exposed to the vacuumatmosphere at least one thereof being at least in part covered withmaterial of lower electro-conductivity than the material of said onesurface to form a resultant exposed surface.

The invention may be implemented for all physical vapor depositiontreating processes, reactive PVD-processes as well as to allplasma-enhanced CVD-processes. It may also be implemented to othertreatment processes if the two surfaces with the covering are exposed insuch a process to a vaccum atmosphere with electrical chargecarriers.Such treatment processes are especially sputterring reactive, or notreactive by which workpieces are sputter etched or are sputter coatedand are thereby biased on predetermined electric potential or areconnected to an electric reference potential or are operated on afloating electrical potential.

The present invention is also especially directed to ionplatingtreatment processes which are reactive or not reactive. It may also beimplemented to evaporation processes e.g. to electron beam evaporationprocesses, arc evaporation processes, evaporation processes with heatedcrucibles, all such evaporation processes being possibly part ofionplating processes. Thus, and as repeated, the invention may beimplemented to all vacuum treatment processes whereat one of theelectro-conductive surfaces is entirely or in part covered with a lowerelectro-conductive material. This may be caused by the specifictreatment process itself or may be due to such a covering at such asurface already provided before the specific treatment process isstarted as e.g. if such a covering is a surface oxidation of a metallicpart to be exposed to the process.

2. Description of Prior Art, General

It is known that always when electro-conductive surfaces are at least inpart covered by a lower electro-conductive material, called an

"isolating covering"

throughout the following description, and are exposed to the vacuumatmosphere containing electrical chargecarriers, a problem may arise bythe fact that the isolating covering will become occupied withelectrical chargecarriers. This especially if electro-magnetical forcefields are applied to the vacuum atmosphere and/or inhomogeneousdistributions of chargecarriers in the atmosphere lead todiffusion-forces in the vacuum atmosphere on such carriers. This mayalso happen at thermical CVD-treatment processes if chargecarriers areadditionally used e.g. for the activation of a surface to be treated soe.g. ion or electron bombardment. The occupation by electricalchargecarriers leads to electrostatic charging of the isolating coveringlike a capacitor up to a degree where such electrostatic fields areestablished that an uncontrolled discharge occurs, e.g. by break-throughor overflash.

Principally this problem was approached up to now in that whenever suchsurfaces--forming a "oneport" or single port set--were to be fed byelectrical energy, as energy generators, AC-generators were applied or aDC-signal generator and additionally, simultaneously and continuously,an AC-signal generator.

In spite of the fact that the said problems of uncontrolled discharges,as break-throughs and overflashings only occure stochasticly distributedin time and during very short time intervals compared to the treatmentprocess working time, one thus remedied these problems by applyingduring the entire treatment process working time permanently by anAC-generator, be it an impulse-generator, or a RF-generator, etc.

SUMMARY OF THE INVENTION

The present invention departs from the recognition disturbing phenomenaonly occur during relatively short time intervals during the overallprocessing time so that the permanent application of an AC-generatorduring the overall processing time is in fact not justified if there areoptions to counteract and avoid the disturbing phenomena by signalcontrol techniques just at the moments and as long as it is necessary toensure a treatment process to be accomplished leading to a desiredresult.

This first object of the present invention is resolved by providing amethod of controlling a treatment process for an object in a vacuumatmosphere containing electrical chargecarriers which comprises thesteps of

providing at least two surfaces of electro-conductive material, at leastone thereof at least in part covered with material of lowerelectro-conductivity than the material of said one surface to form aresultant surface

exposing said surfaces forming an electrical oneport with said resultantsurface to said vacuum atmosphere

connecting an electrical DC-signal to said oneport

controlling the occupation of said covering by electrical chargecarriersby applying in time intervals a further electrical signal to saidoneport, said further electric signal being different from saidelectrical DC-signal

applying said electrical DC-signal during said treatment processconsiderably longer than said further electric signal.

By this method additionally to the DC-signal generator, the signalgenerators may be applied to generate the further electric signal in acontrolled manner just at moments and just as long as considerednecessary i.e. during significantly shorter time intervals then theDC-signal for the treatment process is applied. This leads to the factthat such additional measures, i.e. signal generators may be accordinglytailored to just deliver the power necessitated. The power layout ofsuch additional signal generators may previously be experienced byexperiment.

According to the invention the actual degree of occupation of theisolating covering by chargecarriers may be monitored in real time anddependent on the result of such monitoring, the further electricalsignal may selectively be applied.

Thus, and under this first aspect of the present invention it is avoidedthat a "dangerous" occupation by electrical chargecarriers occurs inspite of electrical DC-feed to the two electro-conductive surfaces.

Departing from the above mentioned recognition the invention has thesecond important object to counteract the electro-static effects of anoccupation by electrical chargecarriers of the isolating covering in thecase that occupation is a desired result of a treatment process as isespecially the case for ionplating. Thereby the electrostatic negativeeffect of such an occupation shall be counteracted and the occupation ofthe isolating covering with the material of the electricalchargecarriers shall be maintained as the desired result of such aprocess.

In this way problems of stochastic discharge shall be resolvedindependent from whether electrical energy is externally supplied to thetwo electro-conductive surfaces considered--the oneport--or not.

This is resolved by a method of controlling a treatment process for anobject in a vacuum-atmosphere containing electrical chargecarriers whichcomprises the steps of

providing at least two surfaces of electro-conductive material at leastone thereof at least in part covered with material of lowerelectro-conductivity than the material of said one surface to form aresultant surface

exposing said surfaces forming an electrical oneport with said resultantsurface to said vacuum atmosphere

repeatetly applying to said oneport in time intervals one of with apredetermined and of with an adjustable repetition rate at least one ofa short-circuit and of a source of electrical charge by means of acontrolled discharge or charge exchange-current path bridging saidoneport.

A most typical example in which inherently to the treatment process anoccupation by electrical chargecarriers is desired, is ionplatingmentioned above. In ionplating processes ions are deposited from thevacuum atmosphere onto a workpiece surface so as to build up a desiredcoating. Thereby these ions are driven to the said workpiece surface bymeans of electric field applied to the vacuum atmosphere. Due to thisiondeposition which is inherent to ionplating processes it was up to nownot possible to grow coatings of not or low electro-conductive materialby such ionplating or to deposit coating onto not or low-conductivesurfaces of workpieces be it of non or bad conductive material or ofconductive material. This because controlled influencing theelectrostatic fields resulting from the desired occupation of theisolating covering with charge carriers, was not possible.

Thus, ionplating as an important process to-which the present inventionis implemented is a process at which

a) by means of an externally applied one directional electric field inthe vacuum atmosphere ions are to be deposited on the surface of aworkpiece which necessitate external application of a desired electricalpotential to the workpiece.

b) the occupation of the said surface with electrical chargecarriers isnot to be counteracted because then the target of ionplating would notbe reached.

By combining the two methods mentioned above some treatment processesand especially ionplating processes under the said isolating coveringcondition become inventively possible.

This is realized by a method of controlling a treatment process for anobject in a vacuum atmosphere containing electrical chargecarriers whichcomprises the steps of

providing at least two surfaces of electro-conductive material at leastone thereof at least in part covered with material of lowerelectro-conductivity than the material of said one surface to form aresultant surface

exposing said surfaces forming an electrical oneport with said resultantsurface to said vacuum atmosphere

connecting an electrical DC-signal to said electrical oneport

controlling the occupation of said covering by electrical chargecarriersby applying a further electrical signal to said oneport said furtherelectrical signal being different from said electrical DC-signal

applying said electrical DC-signal during said treatment processconsiderably longer than said further electric signal and

applying in time intervals said further electrical signal by applyingrepeatetly at least one of a short-circuit and of a source of electricalcharge to said oneport at least one of with a predetermined and of withan adjustable repetition rate by means of a controlled discharge orcharge-exchange current path bridging said oneport.

As was mentioned above isolating covering of the mentioned kind may becoverings which have been formed independently from the treatmentprocess or as an undesired or desired effect during such process. Suchundesired effect may be caused by uncontrolled reaction of contaminatinggases in the vacuum atmosphere and deposition of their reaction productonto surfaces which are exposed to the vacuum atmosphere.Anindependently formed covering may be a contamination layer onelectro-conductive surfaces which has been generated before thetreatment process is started so e.g. by surface oxidation of a metallicsurface or by a previous coating. The said isolating covering may as wasstated also be formed inherently to the treatment process so e.g. atcoating processes of not or low electro-conductive surfaces and/or whencoating surfaces with layers of not or low electro-conductive materialswhereby in latter case the isolating covering is grown by the process.

For treatment processes at which process, inherently, bad or lowconductive materials are not concerned it is common to operate oneportsbetween two metallic surfaces in the vacuum atmosphere by applyingelectrical DC-signal be it e.g. for generating a plasma dischargebetween such surfaces or for biasing workpieces, screens, electrodesetc. In spite of the fact that at such processes, as was mentioned, bador low electro-conductive materials are not concerned it is known thate.g.on metallic surfaces previously exposed to normal atmosphere acontamination layer is built up as especially an oxidic layer. If suchsurfaces are then applied to the mentioned processes their results, atthe start of such a process and as well known to the man skilled in theart, stochastical discharge phenomena as discussed above which aretolerated because the provision of an AC-signal generator just forcounteracting these initial phenomena would not be justified.Nevertheless electrical sources and generators and other electronicdevices coupled to the process apparatus are significantly loaded bysuch initial discharge phenomena be it electrically and/or mechanicallyand/or thermically and must be accordingly dimensioned, protected orfrequently replaced.

It is just this problem which is resolved by the method mentioned aboveunder the first aspect of the present invention without the necessity ofproviding expensive AC-generators.

Summarizing, the present invention thus proposes under its first aspectto resolve the problem to become able to apply DC-signal generators incases in which up to now only combined DC- and AC-generators were usedrespectively dimensioned for continuous operation.

Under the second aspect the present invention resolves the problem tobecome able to deposit onto isolating coverings electricalchargecarriers and thereby to neutralize the electrical charge thereofwithout significantly interfering with the deposition of the material ofthe electrical chargecarriers.

COMPARISON OF THE INVENTION AND OF PRIOR ART

From the U.S. Pat. No. 4,692,230 a method is known by which in a cathodesputtering process from magnetron sputter sources electro-conductive aswell as isolating target materials are intermittently sputtered. Withthe sputtered off material a workpiece is coated. It is most relevantthat in time-spans during which electro-conductive target material issputtered this is performed by DC-sputtering. When the non-conductivetarget material is sputtered this is performed by means of a continuoustrain of monopolare impulses output from an AC-generator. Theseoperating modes are applied intermittently.

The U.S. Pat. No. 4,693,805 describes a process for sputter coatingdeparting from dielectric target objects or for reactive sputtercoating, for sputter etching etc., thus treatment processes in whichinherently not or badly electro-conductive materials are involved andform isolating coverings.

So as to control the electrostatic charge occupation of such isolatingcoverings at a target cathode- and anode-arrangement there is installedan additonal oneport formed between the said target cathode and a thirdauxiliary electrode.

The two oneports, at which the target object forms a common electrode,are electrically fed from respective DC-signal generators viaelectronically controlled series resistant element formed bytransistors. They are fed intermittently with specifically shapedsignal-forms so that in the one cycles the electric potential at thetarget object leads to its sputtering and in the other cycles theoccupation by electric chargecarriers at the said target is removed bybuilding up a removing electric field at the auxiliary oneport.

Whereas the latter U.S. Pat. removed the occupation by electricalchargecarriers by means of an additional "suction circuit" the DE-A- 3142 900 follows the approach to realize intermittently with ionizingcycles neutralization cycles during which built up chargecarrieroccupations are electrically neutralized.

For an ionplating treatment process the DE-A-31 42 900 provides a lowvoltage glow discharge between a glow cathode and an anode. Duringionizing cycles the glow plasma-discharge is initiated and materialevaporated from a crucible as substantially electrically neutralmaterial is ionized and is accelerated onto the negatively biasedworkpiece. In the neutralizing cycles the plasma-discharge and thus thegeneration of ions is interrupted and the electrons generated at theglow cathode are used to neutralize the electric charge formed by theionsurface occupation of the workpiece surfaces. By means of accordinglytailored circuits the glow discharge plasma is operated by means of atriggered circuit.

The EP-A-0 101 774 proposes a technique to avoid for a glowplasma-discharge which is operated in the "abnormal" mode that ittransits into the arc discharge mode. With respect to definition ofthese operating modes reference is made to the U.S. Pat. No. 3,625,848FIG. 1. Thereby there is provided for the glow discharge a currentmeasurement and there is further provided a resistance element so as tolimit the discharge current as an arc is about to occur. By this measurean already prevailing arc discharge between the glow discharge electrodeis extinguished.

The EP-A-0 062 550 proposes to operate a reactive treatment process by apulsed glow discharge. To become able to adjust the workpiecetemperature by means of the temperature of a treatment furnaceindependently from the plasma discharge there is generated a "cold"plasma by lowering the electrical energy fed between subsequent impulsesto such an amount that the plasma discharge is just not extinguished.

From the DE-A-33 22 341 it is further known to counteract the dangerthat at a glow discharge which is operated at high discharge voltage thedischarge mode transits in an arc discharge mode (see also EP-A-0 101774) and that a disadvantage of a plasma discharge operated byDC-current is that the pressure of the treatment vacuum atmosphere andthe temperature therein are mutually dependent. The problem is resolvedby intermittently operating the glow discharge respectively with impulsespikes for initiating the discharge and with subsequent time-spans ofvoltage with a value which just suffices to maintain the glow discharge.Thereby treatment processes are to be performed which are customarilyoperated by DC-generated glow discharges.

The object of the U.S. Pat. No. 3,437,784 is again to prevent a glowdischarge to transit into the arc discharge mode with local arc betweenthe electrodes. This is reached by feeding to the glow discharge oneporta two-way rectified signal of mains-frequency whereby the amplitude ofthe half-waves is so selected that during the one half-wave cycles theglow discharge is initiated and in the other half-wave cycles it isswitched off. Thereby ions which are about to be generated in thedischarge path of an arc discharge about to occur may recombine. If theextent of time-spans, according to the half-wave time-spans during whichthe feeding signal is below a discharge generating level, do not sufficefor recombination, there is generated by means of a mechanicallyoperated synchronious rectifier formed by a series switch arrangementseparation of the feeding voltage from the glow discharge oneportbetween subsequent glow discharge initiating cycles.

The U.S. Pat. No. 4,863,549 describes an RF etching process in which theglow discharge is RF-operated and the sputtering ioncurrent on theworkpiece is adjusted by a medium frequency signal (90 to 450 kHz)whereby it is reached that the amplitude of the medium frequency signalis not to be adjusted by applying an impulse number modulationtechnique.

From the EP-A-0,432,090 a reactive ionplating process is known at whicha glow discharge is operated between a glow cathode and a crucible withthe material to be evaporated and wherein the evaporated material isionized.

A workpiece carrier is operated with a pulsating DC-voltage with respectto electric reference potential be it anode or cathode potential of theglow discharge. With the pulsating operation of the oneport with theworkpiece carrier apparently especially good ceramic coatings at theworkpieces are achieved.

The pulsating DC-voltage is generated as a modulatable square impulsetrain by means of an impulse generator provided therefor.

From the DE-PS-37 00 633 it is finally known to operate a glow dischargeor an arc discharge by means of DC-current square impulses from animpulse voltage source. This to avoid undesired thermical loading of theworkpieces.

Looking back to the present invention:

By means of the inventive methods and especially due to the resultingcontrollability of electrical chargecarrier occupation, principallynovel treatment processes become possible. Already under its firstaspect the present invention is not limited to replacing well knownelectrical feeding by a simplified feeding. Nevertheless alreadyinstalled apparatus with DC-signal operation may be easily amended, byproviding a module which realises the invention, to become able tooperate treatment processes which would not work or would hardly workwithout this additional module with DC-signal operation. This e.g. dueto initial disturbances by oxidic layer on metal surfaces to be treated.

It is a further object of the present invention to realise the inventivemethod as simply as possible.

This is reached by applying the further electric signal by chopperingthe electric DC-signal. By selectively adjusting the repetition rateand/or the duty cycle of choppering, which is preferably realised byparallel choppering, the efficiency of the treatment process may easilybe optimized by applying just during the time-spans necessary and justas often as necessary DC-signal choppering. By coupling a signal with abroad frequency spectrum during optimally short time intervals to theoneport the occurrence of discharge phenomena is prevented thereby onlylowering the electric energy fed to the oneport during optimally shorttime-spans during processing time. By further providing parallelchoppering an optimal combination of the invention under its two aspectsresults namely under the first aspect "DC-signal generator feeding" and"oneport-discharge".

As will be seen at the end of the present description sets of featuresof the present invention and of combinations thereof are summarizedwhich are considered important.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood and objects other thanthose set forth above will become apparent when consideration is givento the following detailed description and to the summarizing list ofimportant features thereof. Such description makes reference to theannexed drawings wherein:

Fig. 1a and 1b show schematically funtional block diagrams ofrespectively known methods or apparatus for electrically feeding aoneport formed between electro-conductive surfaces in a vacuum treatmentatomsphere provided with an isolating covering,

FIG. 2 shows by means of a schematic functional diagram the principleapproach according to the present invention and an electric feedaccording to FIG. 1a or 1b under a first aspect of the presentinvention,

FIG. 3 shows in a representation in analogy to that of FIG. 2 thepresent invention under its second aspect,

FIG. 4 show in a representation in analogy to that of the FIGS. 1 to 3the inventive method and apparatus preferably combining the two aspectsof the invention as shown in the FIGS. 2 and 3,

FIG. 5a to 5c show schematically and heuristically a oneport in a vacuumtreatment atmosphere comprising an isolating covering of not or badlyelectro-conductive material for explaining the charge depositionmechanism and to explain the electrical neutralization thereof accordingto the present invention and to further explain the equivalence circuitwhich is valid for such a oneport at least in a first approximation,

FIG. 6 shows a functional blockdiagram of the inventive method and of aninventive apparatus and of the two aspects of the invention wherebyrespectively under I and II the two aspects of the invention are denotedas combined according to the teaching of FIG. 6,

FIG. 7a to 7c show schematically three examples of inventively adjustingthe discharge or charge exchange behaviour of the oneport by externalfeed of electrical charge, the oneport being represented by itsequivalent circuit,

FIG. 8 shows a functional block/signal-flow-diagram of a preferredembodiment of the inventive method and apparatus according to which thedischarge behaviour of the oneport is monitored and the dischargetime-span is automatically optimized,

FIG. 9 shows schematically the influence of raising thickness of a notor badly electro-conductive coating on the electro-conductive surface ofthe inventively considered oneport on the discharge time constant,

FIG. 10 shows a further embodiment of the invention according to whichthe discharge behaviour of the oneport shown by its equivalent networkis monitored and compared with a rated behaviour and dischargerepetition rate and/or discharge time-span is adjusted by negativefeedback control technique and/or electrical charge, fed to the oneportrespectively,

FIG. 11 shows by means of a functional block/signal flow diagramprincipally the inventive method and apparatus for adjusting theoccupation with electric chargecarriers on an isolating covering whichlatter being formed on one of the two electro-conductive sufaces of theinventively controlled oneport,

FIG. 12a to 12c show a preferred embodiment of the inventive method andapparatus for ionplating with (FIG. 12b and 12c) respectively theequivalent circuits which are valid for the different operating cyclesof the apparatus according to FIG. 12a,

FIG. 13 shows a preferred form of realization of the technique andapparatus according to FIG. 12a,

FIG. 14 schematically shows by means of a functionalblock/signal-flow-diagram a further preferred embodiment of an inventivemethod and apparatus according to FIG. 12a or 13 respectively, by whichthe electrical charge deposition is controlled during operating cyclesof ionplating,

FIG. 15 shows by means of a schematic representation of an apparatusaccording to the present invention a preferred feeding of aplasma-discharge electrode and of an inventively operatedelectro-conductive surface by electric potential,

FIG. 16 shows a further preferred embodiment of the present inventionfor reactive sputtering under the inventive implementation of aDC-signal generator,

FIG. 17 schematically shows by means of a functional block/signal flowdiagram a further preferred embodiment of the inventive method and of aninventive apparatus according to which the rate of occurrence and/or thekind of occurrence of spontaneous discharge phenomena (break-throughs,flashovers) in the vacuum treatment chamber are monitored and as afunction therefrom the discharge and/or the adjustment of the desiredelectric charge deposition is performed in a negative feedback controltechnique according to one aspect of the present invention,

FIG. 18 by means of a schematic functional block/signal flow diagram aninventive method and apparatus at which more than one oneport areoperated mutually staggered in time,

FIG. 19, 19a to 91h show schematically a number of embodiments of thepresent invention in different constellations to show how broad thepresent invention may be implemented.

DETAILED DESCRIPTION FOTHE INVENTION AND OF BEST MODES OF REALIZATION

FIGS. 1a and 1b show prior art methods and accordingly prior artapparatus.

In a vacuum recipient 3 a vacuum atmosphere is confined with carriers ofelectrical charge q. Electroconductive surfaces 2a and 2b, and therebythe area of atmosphere between these surfaces, are electrically operatedso that an electric field becomes effective between the two surfaces.Thereby at least one of the two surfaces 2a and/or 2b is at least inpart covered with material being of low electroconductivity which willbe referred to during the following description as an "isolatingcovering".

The isolating covering may thereby be a contamination coveringindependent from a treatment process performed in the recipient, as e.g.an oxide layer on a metal surface, or may be a coating which has beforebeen applied to an electroconductive surface, which layer is made ofmaterial of low electroconductivity, i.e. of non-conductive or lowconductive material. Further, the isolation covering may be generatedduring a treatment process performed in the recipient, by which acoating of the not or low electroconductive material is deposited. Sucha coating generated during the process considered may be the target ofsuch a process or may be a contamination layer which is unwanted, but isanyway deposited during such process.

The two surfaces 2a, 2b and all structure and atmosphere in recipient 3bridging these surfaces are defined in the following description andclaims as a "oneport" or single port set.

The isolating covering is schematically shown with the reference number4. Except the case where the isolating covering 4 is a contaminationlayer, as e.g. the said oxidic layer on a metallic surface, which e.g.was formed at normal atmosphere, such a oneport between two input tabsto the surfaces 2a and 2b is in a first embodiment customarily operatedwith an AC generator 6, i.e. a generator which generates an at leastsubstantially sinusoidal output signal or, as schematically shown, whichgenerates an output impulse train, possibly with varying duty cycle.

For such conditions FIG. 1b shows a further known approach by which theoutput signal of a continuous AC generator 6b is superimposed as shownat 7 on the output signal of a DC signal generator 6a. This approach isselected because by applying a unipolar electrical field between theelectroconductive surfaces 2a and 2b an occupation layer of electricalchargecarriers will deposit on the isolation covering. E.g., at anegatively biased surface 2b positive electrical chargecarriers, ions,will deposit and there will result, as will be further explained, avoltage across the isolating covering 4. As soon as such voltage reachesrespective limit values according to the local conditions along suchisolating covering, local and spontaneous discharges occur, generallycalled arcing here, be it across and through the isolating covering, beit along its surface and on the electroconductive surface 2b and/or toother neighbouring accordingly electrically polarized parts within therecipient 3.

In FIG. 2, a first principle inventive approach is shown in schematicform and, accordingly, an inventive apparatus. Here the oneport formedbetween the surfaces 2a and 2b must be electrically fed, this accordingto a desired operation for a desired treatment process within recipient3.

The surfaces 2a and 2b are inventively fed by a DC-signal-generator 8. Afurther electrical signal is superimposed to the output of the DC-signalgenerator 8 with a predetermined or adjustable repetition-rate and/orduring predetermined or adjustable time-spans controlled by atiming-unit 10 and, as schematically shown, by a switching unit S. Thefurther electrical signal, generated, as schematically shown, by asignal generator unit 12, is applied to the oneport formed between thetwo surfaces 2a and 2b at predetermined or adjustable time moments andduring predetermined or adjustable time-spans then resulting in anelectrical composite signal which is different from the output signalappearing at the output of DC signal generator 8.

The signal generator unit 12 may thereby be a signal generator which isspecifically tailored for this specific use. Thus such signal generatormay be tailored that, according to repetition rate, at which its outputsignal is superimposed to the output signal of generator 8, andaccording to the time-spans during which such a signal remainssuperimposed, just the specifically necessitated power is delivered tothe oneport. As will be shown later, the unit 12 is construed in apreferred embodiment as a passive unit, by which the output signal ofthe DC signal generator 8 is varied in time and in a controlled mannerbefore being applied to the oneport 2a, 2b.

In FIG. 3 there is shown in an analogue representation the inventiveapproach and an according apparatus under the second inventive aspect,namely that the oneport 2a, 2b must not electrically be power-fed. Thisis e.g. the case when one of the two surfaces is to be operated at afloating electrical potential during a plasma discharge process.Inventively in this case, the two surfaces 2a and 2b on at least onethereof the isolation covering 4 is provided, are bridged. by acontrolled discharge current path, as is shown in FIG. 3 with adischarge switching unit 14, which latter is controlled by a timing unit16. At this unit 16 the repetition rate, i.e. the frequency at which thecontrolled current path is controlled at least for short time-spans tobecome low-ohmic, especially shortened, is predetermined or adjusted.The extent of the time-spans during which the discharge current pathbecomes low-ohmic and substantially short circuits the oneport isadjusted or predetermined by the unit 16 too.

Neither the repetition rate nor the extent of time-spans during which adischarge current is enabled from the oneport 2a, 2b must necessarily beconstant in time during a treatment process considered in the vacuumatmosphere with the carriers of electrical charge q. Both these valuesmay be adjusted dependent from the behaviour of the process anddependent from the kind of process performed in recipient 3.

In FIG. 4 a preferred variant of the inventive method and of aninventive apparatus is shown. Here, the two approaches which wereexplained with the help of FIGS. 2 and 3, are combined. The unit 14bridges the oneport and is controlled by time unit 16. Bridging thecontrol switching-unit 14, there is provided the DC signal generator 8.

As becomes evident and in a most advantageous manner, the unit 14 isoperated as well as a switching unit for closing the controlleddischarge current path and, additionally, operates as the switching unitS of FIG. 2 by means of which the output signal of the DC signalgenerator 8 is varied. Thus, the timing unit 16 simultaneously operatesas the timing unit 10 and 16, according to FIGS. 2 and 3, and furtherthe unit 14 itself operates as unit S and unit 12 of FIG. 2.

In this combined function , the control unit 14 will be referred to bythe reference 14, and the timing unit 16 will be referred to by thereference number 160.

The principle, namely that by the present invention under both of itsaspects, but especially under the second one, shall now be explainedheuristically by means of FIGS. 5a to 5c.

In FIG. 5a there is schematically shown the vacuum recipient 3 andtherein, in the vacuum atmosphere, electrical charge-carriers q, whichare e.g. and especially generated by a plasma discharge PL. The twoinventively operated surfaces 2a and 2b of electroconductive materialare shown and the isolating covering 4. The surface O of the isolatingcovering 4 shall become occupied by positive ions.

There is generated at the surface of the isolating covering 4 adjacentto the surface 2b a layer of electrical charge, which is oppositelyequal to the charge occupying surface O. Thereby, the isolating covering4 forms the dielectric of a capacitor C_(I) which is shown in theequivalent circuit of FIG. 5b. One plate of this capacitor is formed bythe surface 2b, the other plate by the surface O which is disposedadjacent to the vacuum atmosphere, which is due to the electricalchargecarriers q, electrically conductive. The vacuum atmosphere betweensurface O and electroconductive surface 2a may be considered in theequivalent circuit by the impedance Z_(p), whereby, and at least as afirst approximation, this impedance may be further considered as ohmic.This because the movable electrons in the vacuum atmosphere lead, atleast in first approximation, to proportionality of electric field anddisplacement of chargecarriers.

Inventively, namely according to the second aspect of the presentinvention according to FIG.3, the oneport 2a, 2b is intermittently andsubstantially shorted.

If electrical charge-carriers according to FIG. 5a have deposited onsurface O, then a voltage U_(CI) is generated across the capacitor C_(I)as shown in FIG. 5b. If the oneport is shortened by means of switchingunit S₁ , according to the unit 14 of FIG. 3, then the Kirkoff-law muststill prevail, the sum of all voltages along the discharge current pathand the oneport must be zero. Thus, the situation as shown in FIG. 5c israpidly installed: When the switching unit S₁ is closed, a voltage asshown in FIG. 5b and 5c in dashed lines is rapidly installed across theimpedance Z_(p). By this voltage rapidly movable electrons are propelledtowards the surface O. Thereby, adjacent to the surface O, there isformed an electrical double layer without substantial variation of theoccupation of surface O by the material of the ions, which double layerper se is electrically neutral.

Thus, by closing the switching unit S₁, the occupation of surface O byelectrical chargecarriers is electrically neutralized, thereby withoutsignificantly disturbing the material occupation by ion material, whichions are of significantly lower movability than electrons.

Thereby, problems of occupation of the isolating covering by electricalcharge-carriers, as shown in FIG. 5a, which would lead to problems assoon as the voltage U_(CI) across isolating covering 4 reachesbreak-through or spark-over values which would lead to the saidspontaneous arcing, are overcome.

Already here, it shall-be emphasized that only by the described approachit becomes possible to apply coatings of material to surfaces which arenot or badly electroconductive or on bottom coatings of such material orto apply to electroconductive surfaces not or low conducting coatings,all by electrostatic fields. This besides of the resolution which wasdescribed to remedy problems which occur by spontaneous arcing.

The time constant of the electrical discharge or charge exchange-processwhich occurs when the switching unit S₁ is closed, is substantiallygiven by the value of capacitance of the capacitor C_(I) and the"resistance" values in series thereto, which are substantially given bythe movability of the electrons provided in the vacuum atmosphere,according to the impedance Z_(p). This time constant may obviously beinfluenced by external measures at the discharge current path as e.g. byproviding possibly adjustable resistances. If necessary, the dischargecurrent loop, consisting of the oneport and the discharge current path,which provides in a first approximation for a first order system, may bealtered to a system of second order or higher order by adding furtherimpedance elements as e.g. inductivities.

In view of the present invention, it is further important to recognizethat the occupation of the capacitor C_(I), with electricalcharge-carriers after a discharge process may be influenced by applyingan electrical charge source in the discharge current path, generating aflow of electrical charge in the current path.

Further, and especially in view of an ionplating process, it isimportant to recognize that during time-spans in which the switchingunit S₁ is open, one may influence the development of electricalchargecarriers depositing on surface O in an open loop control or evenin a negative feedback control manner by externally supplying electricalcharge to the oneport as will be explained.

Before proceeding with the description of further preferred embodiments,the concept of the present invention under its different aspects shallbe further explained with the help of FIG. 6 taken into considerationthe explanations which were given to FIGS. 2 to 4.

In FIG. 6 the inventive method and the inventive apparatus are shownunder both aspects and in a preferred form of realization in schematicform. The vacuum recipient 3, wherein in a preferred mode of realizationa plasma discharge PL is generated, may be provided with an inlet 18 fora reactive gas or for a reactive gas mixture. Between theelectroconductive surfaces 2a and 2b, i.e. bridging the oneport formedbetween these surfaces, in a first preferred variant of the method andembodiment respectively of the apparatus according to FIG. 4, the unit14_(S) is provided as a chopper unit. Further, the output of the DCsignal generator 8 is bridged by the chopper unit 14_(S) which, thus,acts as parallel chopper unit. The chopper unit 14_(S) is controlled bythe time control unit 160 which is preferably controllably adjustable.

The chopper unit 14_(S), preferably construed by electronic switchingelements, as with transistors, MOSFET'S, TYRATRON's, TYRISTOR'S, sparkgaps, saturated core-inductors etc., controls the discharge current pathof the oneport.

As evident to the man skilled in the art, and as will be specifiedlater, measures may be taken to avoid shortening the output of DC signalgenerator 8 when the switching unit S₁ of the chopper unit 14_(S) isclosed.

Under the first aspect and as framed under "I" in FIG. 6 in dash lines,the invention comprises the simple combination of a DC signal generator8 and of a short circuiting chopper unit 14_(S) by which the oneportbetween the surfaces 2a and 2b at the vacuum treatment apparatus areelectrically operated. Thereby a customary vacuum treatment apparatusprovided with a DC signal generator may be retrofitted in simple manner,namely by providing the chopper unit 14_(S), so as to become able toperform vacuum treatments which would not or hardly be possible by meansof the mere DC signal operation.

Under the second aspect "II", the present invention proposes toexclusively provide a chopper unit 14_(S) provided between two surfaceswhich are not electrically power-fed by a generator. One of which ise.g. disposed on a reference potential, as on ground potential, thesecond customarily operated on floating potential, whereby the electricpotential of the latter electrode results from the distribution ofelectric potentials in the vacuum atmosphere. At such oneports, too, itmay be of great advantage to reduce the effect of electricalcharge-carriers occupating the floating electrode, which influence thefloating potential of that electrode. Thus, the inventive dischargingwith the help of the chopper unit 14, is considered per se as aninventive part of the present invention. This part of the presentinvention is shown within dash-dotted lines at II.

In FIG. 7a provision of a source of electrical charge in the inventivedischarge current path according to FIG. 5 is shown. The source ofelectrical charge becomes effective to the oneport 2a/2b duringtime-spans in which the discharge current path is closed, i.e. when theswitching unit S₁ is closed.

There is provided in the discharge current path, e.g. one source 20 ofelectrical charge Q, which is realized e.g. by a current impulse source.The source Is triggered, as schematically shown, and at leastsubstantially in synchronism with closing of the switching unit S₁ bythe timing unit 16 or 160 respectively, depending therefrom whether theconfiguration shown in FIG. 7a is implemented in the manner shown inFIG. 3 or is implemented in a combined configuration as principallyshown in the FIGS. 4 or 6.

By closing the switching unit S₁ electrical charge of predeterminedpolarity is fed to the capacitor C_(I) and the occupation of surface Owith electrical charge according to FIG. 5a is risen or lowered. Therebyespecially the discharge--or charge neutralization-process may beshortened, in that, and in the extreme, the entire charge occupationprevailing at surface O, i.e. at the capacitor C_(I) is neutralized bythe charge fed from source 20 at the very beginning of the time-spanduring which switching unit S₁ is closed.

In FIG. 7b a first variant is shown for externally influencing thecharge of capacitor C_(I) in a controlled manner. When the switchingunit S₁ is open, a discrete capacitor C_(D) is loaded by a currentsource 22 in a desired polarity and to a desired amount so as indicated,e.g., in FIG. 7b.

When the switching unit S₁ is closed the resulting discharge or chargeexchange process is governed by the values of capacitant at C_(I) andC_(D) and from the respective charging conditions as initial conditions,as is clearly known to the man skilled in the art.

If, in the time-spans in which S₁ is opened, the charge which is builtup on C_(I) is monitored,then it may be neutralized by the chargesource, formed according to FIG. 7b by current source 22 and capacitorC_(D). In the one time-spans the loading condition of the capacitorC_(I) is monitored, in the other time-spans this loading resulting fromoccupation of surface O with electrical chargecarriers, especiallypositively charged ions, is neutralized.

Possibly, the switching unit S₁ may be omitted.

According to the preferred embodiment of FIG. 7c, there is introducedinto the discharge current path a voltage source U_(E) so that thedischarge process is governed by the difference between the voltage atcapacitor C_(I) and the voltage U_(E). Thus, by adjusting the value andthe polarity of the voltage U_(E), the discharge or charge exchangeprocess at capacitor C_(I) may be influenced. In a preferred mode thedischarge process is thus accelerated in that a predetermined remainingvoltage at capacitor C_(I) is reached quicker compared with the casewhere the oneport is just short-circuited.

An important advantage of the inventive discharge or charge exchangeprocess is that such discharging or charge exchanging may be monitoredby measuring. This is realized in a preferred way by a current or acharge measurement at the discharge current path. As an example, thisshall be explained with the help of FIG. 8.

According to FIG. 8 the surface 2b of electroconductive material of theoneport 2a, 2b is laid on electric reference potential Φ_(o). Theoneport is further connected to the switching unit S₁ to the invertinginput of a current or, as shown, charge amplifier 24 of knownconstruction. As further shown, as an example, the differentialamplifier provided is connected with its positive input to the referencepotential Φ_(o). When the switching unit S₁ is shut or closed thereappears at the output of the measuring amplifier 24 the time integral ofthe discharge current as schematically shown over the time axis t. Asshown at reference No. A the measuring result of the discharge or chargeexchange process may be further exploited for a variety of objects whichshall be later discussed.

The output signal of measuring amplifier 24 is preferably led to acomparator unit 26 to which a threshold value W is fed generated by athreshold-value generator 28. As soon as the output signal of theamplifier 24 reaches the threshold value W selected, which indicatesthat the discharge process has dropped to an accordingly predeterminedvalue, e.g. a bi-stable element 30 is reset, which latter opensswitching unit S₁. The bi-stable element 30 may thereby be set by therising edge of the output signal of time unit 16 or 160 which closes theswitching unit S₁.

This results in the fact that the discharge time-span is automaticallyadjusted to be only of that extent which is necessary to reach a desiredstate of charge at capacitor C_(I). Thereby only smallest possibletime-spans are blocked from processing time, the remaining time is stillavailable, especially for process energy feeding from the DC signalgenerator 8 in the configuration according to FIG. 4.

As obvious to the man skilled in the art, the time constant of thedischarge process is significantly dependent from the capacitance valueof capacitor C_(I). Whenever the invention is implemented for coating aworkpiece with an isolating covering as by reactive coating, thecapacitance value of C_(I) drops as thickness of such a coatingincreases.

Thus, and as schematically shown in FIG. 9, by exploiting the signal Aof FIG. 8, the diminishing discharge time constant may be exploited toget information about the increasing thickness d of such coating whichleads to information about the time-course of coating growth.

In FIG. 10 a further embodiment is shown according to which the actualdischarge-characteristic is monitored, is then compared with a ratedcharacteristic and, according to the result of this comparison and inthe sense of negative feedback control, the switching unit S₁ is sooperated so that the actual discharge characteristic is negativefeedback controlled to substantially follow the rated characteristic. ASschematically shown, this is realized in that the discharge currentI_(E) is measured by a current detector 32. A voltage value according tothe current measured is e.g. digitalized with the help of an analog todigital converter 34. The digitalized measuring signal is stored in anactual value storage unit 36. The content of the actual value storageunit 36 is compared at a comparing unit 38 with a rated dischargecharacteristic, which latter is stored in a rated value storage unit 40.

An evaluation unit 42 evaluates differences Δ between the rated valuesand the actual values. The output of the unit 42 acts on one hand onsource 44 of electrical charge which is invertable with respect to itspolarity, so as to affect the respective charging state of the capacitorC_(I) when the switching unit S₁ is opened and thus influencing thecharge occupation of surface O according to FIG. 5a. On the other hand,the output signal of unit 42 is led to a control input of timing unit 16or 160 so as to enlarge or reduce the repetition rate of triggereddischarge processes and/or to vary the duty cycle of an impulse train atthe output of unit 16 or 160 controlling the switching unit S₁. The twopossibilities to feedback the output signal of unit 42 are schematicallyshown in FIG. 10 by the throw-over switch N.

If by appropriate control of the charge source 44, the actual dischargecharacteristics become vanishing, this means that the occupation withelectrical chargecarriers of surface O has been neutralized by theaction of charge source 44. This, too, may be achieved by the negativefeedback control 30, shown in FIG. 10.

Thereby, and as an example, the circuit may be operated cyclicly asfollows:

a) opening of S₁ ; source 44, drives electrical charge on C_(I) whichcharge results in chargecarriers from the vacuum atmosphere depositingon surface O, e.g. namely positive ions.

b) Switching unit S₁ remaining open: source 44 is invertedly operatedfor short time, the charge occupying surface O of positive ions iselectrically neutralized by electrons.

c) Switch unit S₁ is closed, the discharge current I_(E) is measured;depending on the remaining magnitude and polarity of the measureddischarge current neutralizing in repeated step b is adjusted and/or thedeposition of chargecarriers on surface O controlled in step a) isadjusted in a negative feedback control loop.

The effect of external application of a source of electrical charge tothe oneport as e.g. of source 44 in time-spans, during which theswitching unit S₁ is open, will be further explained. This especially inconnection with ionplating of workpieces as one important part of thepresent invention.

By influencing the state of electrostatical charge at capacitor C_(I)and/or on the repetition rate of discharge and/or the extent ofdischarge time-spans, one may influence the occupation of surface O withelectrical chargecarriers in a negative feedback controlled manner, sothat, as long as the capacitance value of capacitor C_(I) remainssubstantially constant in time, the discharge characteristic and thusthe said occupation with chargecarriers is maintained substantially on arated value. This even then, when the discharge time constant varieswith varying capacitance value of C_(I). In this case one may evaluatethe instantaneous value of that capacitance from the discharge timeconstant and then from the value of that capacitance thus found and bythe initial value of the discharge process conclude on the occupation ofsurface O by chargecarriers, especially by ions.

According to FIG. 11, and departing from the representation of FIG. 3 orfrom a combined configuration according to FIG. 4, according to oneimportant aspect of the present invention, in time-spans in betweensubsequent discharge timespans, the occupation of the isolating covering4, according to FIG. 5a, with electrical chargecarriers may be adjustedin an open control loop manner or in a negative feedback closed loopcontrol manner.

Therefore, attention is again drawn to FIG. 5. If in FIG. 5 anelectrical charge is enforced externally to the oneport comprising thesurfaces 2a and 2b then, clearly, capacitor C_(I) is charged. If, andaccording to current direction convention, in a current i which accordswith an electrical charge per time unit is fed, this results in anincrease of the charge occupation by positive ions at the isolatingcovering 4. If the current direction is inverted, this results in adecrease of occupation by electrical charge, i.e. results in positiveions being removed from the surface O and or electrons being drawntowards said surface. Attention shall be drawn to the fact that it iscustomary that the direction of current i is defined opposite to thedirection of electron current.

Thus, by external feeding a current or an electrical charge to theoneport, the occupation with electrical chargecarriers of the isolatingcovering may be controlled. This is of predominant importance,especially for all those treatment processes in which just by such anoccupation with chargecarriers and with the corresponding occupationwith material, a coating shall be built up which is especially the casein ion-plating process. There, ions out of the vacuum atmosphere arecontrollably deposited on the surface of a workpiece by means ofelectrostatic forces.

For this object, according to FIG. 11, when the switching unit S₁ isopened at the unit 14 or 14_(S) according to the FIGS. 3 or 4, by meansof the timing unit 16 or 160, a flow of electrical charge is generatedthrough the oneport 2a, 2b, as is shown in FIG. 11 schematically by thecharge source 46 which is enabled synchronously with switching unit S₁.

Thereby, at the said treatment processes and especially at an ionplatingprocess, the deposition of a layer or coating on the non or badlyconductive surface of a workpiece or the deposition of a layer orcoating made of non or badly conductive material on either conductive ornot conductive surfaces of a workpiece may controllably be influenced,be it controlled in open loop manner or in negative feedback controlledmanner.

In FIGS. 12a to 12c, schematically, a preferred variant of thisinventive method is shown and respectively of a preferred apparatus. Inthe recipient 3, material is evaporated from a crucible 52, e.g. bymeans of a plasma discharge. This may be done by means of an arcdischarge to crucible 52 or by electron beam evaporation of material inthe crucible 52 or, as shown, by means of a glow discharge, especiallyby a low voltage glow discharge generated between an electron emittercathode, so e.g. a glow filament cathode 50 and crucible 52. It is clearthat material may also be evaporated by heating the crucible or may besputtered. It is only of predominant importance that the material in theatmosphere is ionized, whereby it is of less importance how the sourceof that material is construed and by which process the material is freedinto the vacuum atmosphere. Further, such a process may be operated in areactive gas atmosphere, so that the material freed in the vacuumatmosphere first reacts with a reactive gas before depositing or suchprocess may be non-reactive. Through the gas inlet 18 and according tothe embodiment shown, a working gas is inlet to the vacuum recipient 3,at least comprising reactive gas, which reacts in the glow dischargewith the material evaporated from crucible 52. Ions are formed. As areaction product, non or badly electroconductive material deposits inthe form of positive ions, thus first forming an occupation ofelectrical chargecarriers onto one or more than one workpieces 1, whichare deposited on one of the electroconductive surfaces, e.g. surface 2a,which thus acts as a workpiece carrier surface. The workpieces 1 therebyhave either intrinsically an electroconductive surface and are coated bythe ionplating process with a coating of non or badly conductivematerial or such workpieces intrinsically have a surface of non or badlyconductive material and are then ionplated with a layer or coating ofeither non or badly conductive material or of electroconductivematerial.

The method allows on one hand ionplating with non or badly conductivecoatings on all kinds of conductive or non conductive surfaces orionplating conductive coatings on non or badly conductive surfaces atworkpieces, said surfaces being formed either by previously depositedcoatings or by the intrinsic surface of the workpiece. Suchcoating/workpiece systems could up to now only be realized by ionplatingto a very restricted amount. This because the unipolar plating currentnecessary could not be realized to a sufficient amount and duringsufficient time-spans.

Further, the workpieces 1 may be provided in the apparatus according toFIG. 12 or in other configurations which will be described later, withmulti-coating systems too. Thereby especially workpieces made ofmaterial of any electric conductivity may be provided with a non or badconductive first layer, especially as a corrosion protective layer, thenwith a second layer of electroconductive material, especially as a wearresistance layer, or with a combination of such layers comprising morethan the said two layers.

For ionplating it is important that the material to be deposited is, aswas mentioned, ionized in the vacuum recipient. This may be realized indifferent manners. Material evaporated by electron beam may be ionizedby means of a plasma discharge, as e.g. by an arc discharge on thecrucible. For arc evaporation or glow discharge evaporation, ionizationoccurs by means of the plasma discharge itself. Alternatively oradditionally electrons or ions may be fed into the vacuum recipientwhich improve or lead to the desired ionization. Further, and as wasmentioned before, other than reactive processes may be performed if,e.g., the evaporated material shall be deposited as it is freed into theprocess atmosphere after ionization.

Further, instead of evaporation, the material may be sputtered. If anelectroconductive material is sputtered, a sputtering source, as e.g. amagnetron source, may be provided instead of crucible 52. If anon-conductive material shall be sputtered, the sputtering source ispreferably operated separately by means of an RF plasma discharge.Thereby the crucible 52 is replaced for implementing of the presentinvention by an electroconductive surface, independent from the RFdischarge as a reference surface in the recipient (see e.g. FIG. 19f).

In every case the conductive surface 2a acting as a workpiece carriersurface is to be connected to an electrical potential so that forionplating positive ions are accelerated towards the workpieces 1 toform the said occupation by electrical chargecarriers, the positiveions. The electric power which is necessary to be applied at the oneport2a/2b is significantly lower compared to the electric power necessaryfor maintaining a plasma discharge which is eventually to be generatedin the crucible.

According to the embodiment of FIG. 11, the plating current which isexternally applied, accords with the ion and electron propagation inbetween the electroconductive surfaces 2a and 2b. At least one of theelectroconductive surfaces 2a and 2b, preferably that one 2a which actsas workpiece carrier surface according to FIG. 12a, is connected to adiscrete capacitor C_(D1). The switching unit S₁ closes the dischargecurrent path to the second electroconductive surface 2b. This secondelectroconductive surface 2b is formed by the crucible in the case ofevaporation or by a sputter source in the case of sputtering aconductive or semiconductive material. There is provided a current orelectrical charge source 46a (compare FIG. 11) which, when the switchingunit S₁ is open, as shown in FIG. 12b, appears in series to the discretecapacitor C_(D1), the capacitant C_(I) and the impedance Z_(p) of thevacuum atmosphere between the two surfaces 2a and 2b. When the switchingunit S₁ is closed and as shown in FIG. 12c, the current or electricalcharge source 46a is shortened via the closed discharge current path.

This apparatus operates as follows:

In time-spans of ionplating, i.e. in processing timespans, during whicha layer is deposited on the workpieces 1, the switching unit S₁ isopened. During these timespans an electrical charge, e.g. in the form ofa current impulse, is driven through the series connection according toFIG. 12b by the source 46a which is e.g. realized according to FIG. 12band 12c as a current impulse source. The polarity of the electricalcharge fed, according to the time integral of current, is selected asshown. Thus,both the discrete capacitor C_(D1) and the capacitor C_(I)of the oneport are charged, whereby the electric field E which isgenerated in the vacuum atmosphere between the surfaces 2a, 2b acts soas to drive positive ions towards the workpieces 1 as shown in FIG. 12b:There is deposited at the surface O of the isolating covering on theworkpiece, i.e. on its non or badly conductive surface, an occupation ofchargecarriers which accords to the current i which was fed during suchplating time interval.

Thereby, it becomes evident that the amount of electrical charge, whichis externally fed by means of the source 46a, accords at leastapproximately to the amount of electrical chargecarriers (ions) whichare deposited in these plating time intervals on the workpieces 1. Byvarying the externally applied electrical charge in the plating timeinterval, thus, the degree or amount of electrical charge deposition andthus, the grow rate of coating is varied. After or between such platingtime intervals, the switching unit S₁ is closed as was described above.

The capacitant of the oneport which was described before, as well as thediscrete capacitance C_(D1) act initially, as is well-known, as a shortcircuited element. When the switching unit S₁ is closed, theconfiguration as shown in FIG. 12c becomes valid. The equivalent circuitelements which now appear in parallel, namely especially capacitanceC_(I) and capacitor C_(D1) are first still charged to equally directedvoltages as shown in FIG. 12c, so that the discharge process of thediscrete capacitor C_(D1) accelerates the discharge or charge exchangeprocess of capacitor C_(I). The time constant of the overall dischargeprocess is given by the series connection of the two capacitiveelements, so that by selection of the value of capacitance C_(D1)significantly larger than the value of the capacitance C_(I), the timebehaviour of the discharge process remains predominantly given by C_(I)and the impedance Z_(p). The charge applied to capacitor C_(D1) is (FIG.12b) substantially equal to the charge applied to C_(I) due to seriesconnection, so that the said discharge process, according to FIG. 12c,is in fact accelerated by which the voltages in the parallelconfiguration of FIG. 12c are brought to equal value when the transientdischarge process is terminated.

It is evident that after transient discharge, the voltages at C_(D1) andC_(I) are, in the parallel structure, oppositely directed and of equalvalues.

Because, and as was explained above, during the discharge processsubstantially only the electrical charge of the occupation ions isneutralized and not the occupation with the material particles of theions, there occurs during the discharge process no significant variationof the ion particle layer which has already been deposited and is nowjust electrically neutralized.

In FIG. 12a there is shown a further improvement of this preferredembodiment, especially for ionplating. Thereby, and as was alreadydescribed, the discharge current is measured, the respective measuringsignal is possibly analog to digital converted in the converter 34 andis stored as actual value in the actual value storage 30. The content ofthe storage 30 acting as a data buffer is compared at the comparing unit38 with the rated value stored in rated value storage 40. Thereby,significant values of the respective actual and rated dischargecharacteristics are compared.

The evaluation unit 42 evaluates the result of actual to rated valuecomparison Δ, possibly under consideration of the varying time constantas a function of varying values of the capacitance C_(I) due to coatingthickness increase. In the sense of negative feedback control, theoutput signal of unit 42 acts on a control input of source 46a so thatthis source is controlled to adjust the actual discharge characteristicor its significant parameters to at least substantially become equal tothe rated discharge characteristic or its characteristic parameters.Thus, it becomes possible to accurately control the growth of layer byadjusting the occupation of the respective surfaces at the workpieces 1,according to surface O of FIG. 5, during time intervals of platingdeposition and thereby, additionally, to avoid the occurrence ofdangerous voltages across the respective isolating covering 4 accordingto FIG. 5 with respect to general arcing, by neutralizing the electricalchargeplating deposited during discharging time intervals.

In FIG. 13 a further improvement is shown, namely a very simple form ofrealization of the technique, which was explained for the embodiment ofFIG. 12. Therefrom it will become evident that now the invention isrealized under its combined aspect which was explained in connectionwith FIG. 4.

With respect to the treatment chamber in recipient 3 the same conditionsprevail which were described in connection with FIG. 12. The main objectis to realize in a most simple way source 46a of FIG. 12. This is donein that the output of the DC signal generator 8, according to FIG. 4,acts via a choke L₆₆ on the network which was described in connectionwith FIG. 12a instead of the source 46a.

The DC signal generator 8 is e.g. poled according to the voltage U_(B)of FIG. 13. When the switching unit S₁ is closed and first withoutconsidering unit 56, a current flows through the choke L₆₆ and over theclosed switching unit S₁. The current which then flows is shown in FIG.13 at I₁. As soon as the switching unit S₁ is opend for starting aplating time interval there is generated across the choke L₆₆, a highnegative voltage impulse, as schematically shown at U_(L66). Thisvoltage impulse drives through the series connection of C_(D1) andC_(I), as was explained in connection with FIGS. 12b, the electricplating charge. After this transient caused by U_(L66) the voltage U_(B)lays commonly across the capacitors C_(I) and C_(D1). By the choke L₆₆the transient plating process is accelerated in this plating timeinterval. The operation remains qualitatively the same if the choke L₆₆is omitted and the voltage U_(B) is directly applied to the seriesconnection of the two capacitive elements C_(I) and C_(D1) when theswitching unit S₁ is opened.

Thereby, one must make sure that the DC signal generator 8 is capable tohold its output voltage to rapidly charge the capacitive load whichappears at its output.

When the choke L₆₆ is provided, e.g. an electronically variableresistance element may be provided in the discharge current path, soe.g. a transistor stage 56, which is controlled from the output of unit42, according to FIG. 12a, and which varies the current which flowsthrough the choke L₆₆, when the switching unit S₁ is closed. By varyingthis current the peak value of the voltage impulse U_(L66) is varied andthus the time behaviour in the transient plating time intervals. Byvarying the resistance value at the stage 56 to be different in platingtime intervals and in discharge time intervals, the stage 56 can be madeof no influence during discharge time intervals, i.e. forming a shortcircuit, or may be used in these time intervals, too, to adjust thetransient discharge characteristic. Thereby, the switching unit S₁ mayevidently be combined with the transistor stage 56, which latter thenacts as controlled resistance stage forming the switching unit.

It is further evident that it is absolutely possible to preselect theresistance value of stage 56 without providing a measurement ofdischarge current and negative feedback, as was shown in FIG. 12a, andthus to adjust the stage 56 e.g. during first adjusting experiments andthen to operate the stage 56 just synchronized with the timing unit 16,160 of FIG. 12.

In a further alternative embodiment to that of FIG. 13, FIG. 14 shows afurther preferred variant. Thereby, a highly efficient and accuratelycontrolled transfer of electrical charge is realized in plating timeintervals, i.e. a highly efficient control of coating deposition inthose time intervals. Thereby, to the arrangement of FIG. 12a, there issuperimposed to the output signal of DC signal generator 8 a voltagesignal as shown with source 58, the output voltage of which having apredetermined or adjustable course with respect to time, i.e. having apredetermined characteristic of dU/dt.

This source 58 is triggered by the output signal of time unit 16 or 160at a trigger input T_(r) in the plating time intervals, i.e. when theswitching unit S₁ is open. As is shown in FIG. 14 at the bottom, thesource 58 may generate e.g. a linear or a progressive output ramp oranother output voltage curve form with a predetermined characteristic ofits time derivative being triggered, according to a desired growth rateof an ionplating deposited layer. Due to the time differentiatingcharacteristic of the series connection of the two capacitive elementsC_(I) and C_(D1) there results from as dU/dt known the correspond scurrent flow i.e. corresponding electric charge flow per time unit. Thistime derivative dU/dt may also be applied for source 44 in FIG. 10 as anadjusting value in the negative feedback control loop.

As has already been discussed in connection with FIG. 13, according toFIG. 14 a desired time course of the time derivative may be preselectedor may be adjusted within a negative feedback control loop, e.g. by theoutput signal of a unit 42. Thereby in plating time intervals a desiredoccupation by chargecarriers is achieved which, as was mentioned, ismonitored during the discharge time interval to be readjusted in thesaid negative feedback control sense. Adjusting the plating current isshown in FIG. 13 in dash lines. Instead of providing an additionaltriggered voltage source, the output voltage of the DC signal generator8 is varied in synchronism with the output signal of the timing unit 16or 160 to provide for desired dU/dt.

The method explained with the help of the FIGS. 11 to 14, is mostadvantageously combined with an ionplating treatment pross. Thereby, anovel ionplating method is created with the ability to applyelectroconductive coating on non-conductive surfaces or to applynon-conductive coatings on conductive or non-conductive surfaces.

The method as has been explained with the help of the FIGS. 12 to 14,for controlling the charge occupation of the surface O according to FIG.5 during plating time intervals is considered per se as an inventionwhich, obviously, may be most advantageously combined with otherfeatures described.

At all embodiments of the inventive method or apparatus at which,according to FIG. 4, the oneport 2a, 2b is fed from a DC signalgenerator 8 via a chopper unit 14_(S) or via a chopper switching unit S₁and a plasma discharge PL is generated in the vacuum recipient, as shownschematically in FIG. 15 between plasma generating electrodes 60a and60b, electrical instabilities are avoided in that one of the electrodesloaded with plasma discharge current, as e.g. electrode 60b, isconnected to an electric potential at the discharge current path.Preferably one of the inventively provided two electroconductivesurfaces of the oneport is further used according to FIG. 15 as plasmagenerating electrode. This is clearly shown by the connection 62 in FIG.15.

In FIG. 16 a further preferred embodiment of the inventive method andapparatus is shown. In the vacuum recipient 3 a glow discharge isgenerated, e.g. between the wall of the recipient 3 and a target 64 ofconductive or at least semiconductive material. By means of a gas feed18 a working gas with a reactive gas is inlet in the recipient 3. Thus,FIG. 16 shows an apparatus for a reactive cathode sputtering process.The target 64 may be a part of a magnetron sputtering source. Theworkpieces are not shown in FIG. 16. They are either operated floatinglyor are driven at a biasing potential, e.g. as was shown at FIGS. 11 to14 for ionplating. The glow discharge in the embodiment of FIG. 16 isoperated principally according to FIG. 4. After the explanations whichwere given, the embodiment of FIG. 16 must not be explained for the manskilled in the art in details. Because the DC signal generator 8 foroperating the glow discharge necessitates relatively high output power,when the switching unit S₁ is closed by the timing unit 160, thusgenerated in phase-opposition thereto, a series switching unit S₂ isopened, so that the glow discharge current may not flow through theswitching unit S₁. Especially when the DC signal generator 8 has theoutput characteristic of a DC current source, the switching unit S₂ ispreferably bridged by a network, preferably by a resistance network, asis shown at R in FIG. 16, but may also be bridged by an electroniccontrol network as by a transistor network.

Thereby, it is reached that, when switching unit S₂ is open, not toohigh voltages occur across the open switching unit S₂.

The measures which have been described before, so e.g. provision of apossibly controlled voltage source U_(E) according to FIG. 7c toinfluence discharge process or the measures for measuring the dischargeprocess and accordingly influencing the timing unit 160, as wasdescribed with the help of FIG. 8, will be implemented preferably alsoin this embodiment. Especially the features of FIG. 8 allow in the caseof cathode sputtering, e.g. according to FIG. 16, to optimize efficiencyof the apparatus in that the discharge timespans are optimally adaptedand adjusted to the shortest possible extent.

For the inventive ion plating according to the FIGS. 11 to 14,preferably the output signal of the DC signal generator 8 is varied at arepetition rate according 50kHz to 500 kHz, preferably of at least90kHz, and especially preferably with at least 100 kHz which results inoperating the switching unit S₁ at the said frequency, i.e. the timingunit 16 or 160. The closing times of the switching unit S₁ are therebypreferably selected to be 50nsec and 10 μsec preferably between 0.5 μsecand 2 μsec or between 2 μsec and 10 μsec, also in dependency from theabove mentioned repetition rate selected and from the intended treatmentprocess to perform, especially from the intended ionplating process. Ifsputtering is performed, as was explained with the help of FIG. 16 asone preferred embodiment, operating frequency of the switching unit S₁according to repetition rate with which the output signal of the DCsignal generator 8 is varied is selected preferably to be between 50Hzand 1 MHz futher preferably between 5kHz and 100 kHz, thereby especiallypreferably between 10 kHz and 20 kHz (all limits included). Here too,the time interval, i.e. the closing timespans during which the switchingunit S₁ remains closed, are selected to be between 50 nsec and 10 μsec,preferably between 0.5 μsec and 2 μsec or between 2 μsec and 10 μsec,dependent on the desired treating process and the selected repetitionrate respectively.

The inventive method which was described with the help of FIG. 16 isespecially suited for generating silicon oxide coatings, i.e. coatingsof Si_(x) O_(y). The method is extremely suited to be applied inconnection with a sputtering cathode of a mixture of indium oxide andtin oxide or of indium and tin, which material being sputtered into anatmosphere containing oxygen to realize a respective coating at theworkpieces. The same apparatus may also be used for sputtering insteadof a target the surfaces of workpieces,to perform sputter-etching, or tosputter-etch the surface of a target, so as to remove e.g. acontamination layer as e.g. an oxide layer or other undesireddepositions.

The reactive cathode sputtering process, as it was described inconnection with FIG. 16, may be operated in the oxidic (reactive) or inthe transition mode, whereby, and with respect to definition of theseoperating modes, it is referred to "reactive DC high rate sputtering asa production method" ("Reaktives DC-Hochratezerstauben alsProduktionsverfahren") of S. Schiller et al., speach to theInternational Conference on Metal Coating, San Diego/Calif., March 1987,Surface and Coating Technology 33 (1987).

Thereby, it has been recognized that with the inventive cathodesputtering method, the transition from the metallic to the reactive modeis considerably less abrupt as is customarily expected. This means thatwith the inventive method the characteristic of the per se instabletransition mode, the so-called intra-mode, becomes flatter than it wouldbe expected, and that thus a process working point is significantlyeasier to stabilize inventively in this intramode than with othermethods by means of negative feedback control.

In FIG. 17, a further preferred embodiment is shown which has to beconsidered in connection with that of FIG. 16. Nevertheless, theembodiment and method according to FIG. 17 may also be implied inconnection with ion plating or with other treatment processes. Somefurther examples shall later be disclosed with the help of FIG. 19.Without limiting, this further improvement is shown in FIG. 17 on thebasis of the cathode sputtering method according to FIG. 16.

Instead of measuring the discharge current here and as an example, thereis provided a current detector 66 to monitor e.g. the glow dischargecurrent. With monitoring the current I_(S), the occurrence ofstochastical arcing, be it overflashing or breakthroughs, is registeredwhich arcing may be recognized by the occurrence of current spikessuperimposed on the discharge current I_(S). Instead of monitoring thecurrent, stochastic arcing can also be monitored by an optical detectorin the vacuum recipient. The characteristic of the current monitored bydetector 66 is evaluated in an arc occurrence detection unit 68. Theoutput signal of the arc detection unit 68 is led to a comparator unit70. Therein it is monitored at which repetition frequency the saidstochastic arcing occurs and/or at which intensity which is recovered byanalysing the occurrence and the shape of the said current spikes. Theevaluated actual characteristic value, be it intensity and/or rate ofrepetition, is compared in unit 70 with a predetermined rated value forthis characteristic value, predetermined at unit 72. The output of unit70 adjusts via a controller 73 the inventive arrangement framed inbroken lines in block 74 of FIG. 17. Thereby, the occurrence of arcingis monitored instead of monitoring the discharge current.

With the controller 73 the repetition rate and/or the extent oftimespans during which the switchin unit S₁ is closed, is controlled viatime control unit 16 or 160, this also for a oneport which is notelectrically actively fed, in contrary to the embodiment of FIG. 17 forcathode sputtering, i.e. for a oneport with no DC signal generator8-feed.

If e.g. the occurrence frequency of stochastic arcing is too high, therepetition rate of closing the switching unit S₁ is risen and/or thetimespans during which the switching unit S₁ closes the dischargecurrent path are enlarged. By these features, too, an optimal efficiencyis reached, in that the discharge timespans are generated only so oftenand so long as necessitated by the actual arcing behaviour of theprocess.

Especially the repetition rate of installing the discharge or chargeexchange timespans is adapted to the actual growth of an isolatingcovering. Thereby, automatically, the efficiency of the processing plantand apparatus is optimized.

Measuring apparatus for detecting the said arcing characteristic inplasma discharges and especially in glow discharges are known.

The just described method of FIG. 17 is preferably applied incombination with a cathode sputtering apparatus as was shown inconnection with FIG. 16.

In FIG. 18 a further most important embodiment of the inventive methodand apparatus is shown, which is especially important for ion platingaccording to the FIGS. 11 to 14. Nevertheless, the methods andprinciples shown here are not exclusively applicable for ion plating.FIG. 18 shows, nevertheless, and without being limiting, suchimprovement for ion plating as was disclosed in connection with theFIGS. 11 to 14.

In FIG. 18 parts, which were already described in connection with FIG.12, are referred to with the same reference numbers. In the vacuumrecipient 3 there is performed in one of the pre-described mannersionplating, e.g. with an evaporating crucible 52 which forms the one ofthe two electroconductive surfaces of the inventively exploited oneport.A glow discharge or another plasma discharge according to thedescription to FIG. 12 is here not shown. Several workpiece carriersurfaces 2a₁, 2a₂, 2a₃ . . . 2a_(n) are provided on which workpieces 1to be ionplated are deposited. The respective pairs of inventivelyoperated electroconductive surfaces 2a_(x) and 2b are respectively andas only schematically shown here operated by an inventive operatingblock B_(x), realized as was explained in connection with the FIGS. 11to 14.

If at such a configuration all switching units S₁ schematically shownare simultaneously closed, then significant energy is removed from thetreating process and especially from the plasma discharge if the processis operated with such plasma discharge. This leads to instabilities inthe process control.

Therefore, and according to FIG. 18, there is provided a supervisingtime control unit 162 which controls e.g. via a time staggering unit 71,realized e.g. by a shift register unit, each of the units B₁ to B_(n)cyclicly and in a time staggered manner. This is schematically shown onthe time axis t by time staggered control impulses to each of the unitsB_(x). If it is desired to operate each of the oneports 2a_(x) /2bseparately and separately in an optimized manner, then for each of theseoneports there is provided a time control unit 16 or 160, according toFIG. 12, and each of the oneports is operated according to the FIGS. 11to 14, whereby a synchronization unit makes sure that via the timingunit 16 or 160, as shown in FIG. 18, the oneports are dischargedstaggered in time. It is evident that possibly more than one workpiececarrier surface 2a, may be operated together so as to form groups, whichgroups of surfaces 2a_(x) are operated in a time staggered manner.

Further, it must be emphasized that with the chopper unit 14 or 14_(S),which has been explained with the help of FIG. 6 and the followingfigures, a large number of existing vacuum treatment apparatus with DCsignal generator feed may be retrofitted so that with such retrofittedapparatus processes become realizable for which, up to now, completelydifferent apparatus and plants were to be used, especially withdifferent generators as was explained in connection with FIG. 1.

Thus, with one and the same apparatus treatment processes may berealized which, on one hand, necessitate DC operation and which, on theother hand, could not be realized with DC operation up to now but whichapparatus can now be operated for such treatments too by the mere factthat the present invention is implemented.

In FIG. 19 some possibilities of implementing the present inventionshall be further explained, without being complete and without intent oflimiting the invention, just so that the man skilled in the art gets theclear idea, where and how the present invention may be applied.

FIG. 19 departs from a workpiece 1 made of non or low conductive tivematerial which, thus, forms itself the isolating covering. In the vacuumrecipient 3, a plasma discharge PL is initiated in known manner. Theworkpiece 1 may be subjected to etching or may be coated with aconductive or non-conductive layer, be it by evaporation ofelectroconductive or non-conductive material, reactive or non-reactive,or sputtering of conductive or semi-conductive material, again reactiveor non-reactive. The inventive operational unit, as was describedbefore, is schematically shown with block 5. In FIG. 19a, departing fromthe general representation of FIG. 19, a plasma discharge is shownbetween plasma discharge electrodes 80a and 80b, which plasma dischargeis generated by a DC or AC current generator 82, specially foreseen tofeed the plasma discharge. The treating process may be e.g. ionplating.The inventively operated electroconductive surfaces 2a and 2b areoperated independently from the plasma discharge. If e.g. non or lowconductive material shall be sputtered, so as to afterwards be depositedin a reactive or not reactive deposition process on the workpieces 1,one may see that the generator 82 is preferably provided as an RFgenerator in known manner.

According to FIG.19b, the plasma discharge PL is sustained by the fieldof an induction coil 84. With respect to operating the inventivelyprovided electroconductive surfaces 2a and 2b forming the oneport,nothing changes with respect to FIG. 19a.

According to FIG. 19c, again a plasma discharge is maintained betweenplasma discharge electrodes 80a and 80b, whereby here one of the plasmadischarge electrodes, so e.g. the electrode 80b, is used as one of theinventively operated conductive surfaces, e.g. as surface 2a.

According to FIG. 19b, a workpiece 1 is e.g. etched in a plasmadischarge, whereby here the electrodes 80a, 80b respectively formsimultaneously the inventively operated conductive surfaces 2a and 2b.

With the plasma discharge according to the FIGS. 19a, 19c, a materialdisposed on one of the plasma discharge electrodes may be sputtered tobe directly deposited on a workpiece 1 or to be deposited on such aworkpiece after reaction with a working gas or with parts of such aworking gas within the recipient 3. Equally, evaporated material may beionized with the plasma discharge shown to be deposited by ionplating onthe workpieces, be it unreacted or after reaction with a reactive gasled to the vacuum recipient 3. Principally, how the material sources andits ionization are realized in the vacuum recipient are of secondaryimportance for the present invention. Of prime importance is thatworkpieces with an isolating covering are treated in a vacuum atmospherecomprising electrical charge-carriers.

One can apply arc evaporation, a so-called rod feed technique, electronbeam evaporation, thermical evaporation or sputtering, all reactive ornot reactive, and further plasma enhanced chemical wafer deposition(PECVD).

According to FIG. 19e, a target 85 made of electroconductive or at leastsemi-conductive material is sputtered in the plasma discharge and thesputtered off material is deposited without or with additional reactionwith a reactive gas in recipient 3 as an electroconductive or a notelectroconductive or low electroconductive layer on workpiece 1. In thefirst case, the workpiece comprises a non or low conductive surfacewhich may have been realized by previous coating or which is inherent tothe workpiece material.

Both, the plasma discharge and the oneport, may be operated between theconductive surfaces 2a and 2b₁ as well as between 2a and 2b₂inventively. Principally and preferably, pairs of electroconductivesurfaces are inventively operated, whereon deposition of non or lowconductive material is to be considered or at which such materials areprovided.

According to FIG. 19f, in a RF plasma discharge non or low conductivematerial of a target 87 is sputtered and is possibly reacted with areactive gas inlet through an inlet arrangement 18. A layer of non orlow conductive material is ionplated on workpieces 1, whereby in thiscase the workpiece carrier electrode is formed by one of the inventivelyoperated electroconductive surfaces, 2b, and the secondelectroconductive surface 2a is provided separate from the plasmadischarge.

According to FIG. 19g, there is operated a plasma discharge betweenelectrodes 80a and 80b, so e.g. a glow discharge, and there isevaporated material from a crucible 89, an electroconductive material, anot electroconductive material or a material of low electroconductivity.In the plasma discharge the evaporated material is ionized and depositedby ionplating on workpiece 1, so as to form there a layer of respectivematerial. Here too, a reactive process may be operated, in that throughthe gas inlet 18 a reactive gas is fed to the process-atmosphere.

The glow discharge electrodes as well as the oneport between the twoelectroconductive surfaces 2a and 2b are inventively operated asschematically shown with the two blocks 5.

Finally, FIG. 19h shows an embodiment of the invention in analogy toFIG. 19g, whereby here the plasma discharge is generated for ionizingevaporated material by the field coupled into the recipient 3 andgenerated by an induction coil 91.

The example shown and described may show to the man skilled in the artto which an extent the present invention may be applied.

Example for inventive cathode sputtering:

    ______________________________________                                        1)  apparatus:            BAS 450 of the firm                                                           Balzers AG, Balzers/FL                                  cathode:              AK 510 of the firm                                                            Balzers AG                                              magnet system:        MA 525 of the firm                                                            Balzers AG                                              target:               S10-2403 silicon                                                              target (5 × 10 inches)                            DC power supply:      10 kW                                                   distance between target and substrate:                                                              70 mm                                                   rotation-frequency of workpiece carrier:                                                            <0.5 Hz                                                 frequency (repetition rate)                                                                         17 kHz                                                  of inventive discharge:                                                       timespan of discharge:                                                                              9 μsec                                               kind of discharge:    short circuit                                           sputtering power:     2 kW                                                    gas pressures in the recipient:                                               Ar:                   pAr = 8E - 3 mbar                                       O.sub.2 :             pO.sub.2 = 2E - 3 mbar                                  DC voltage at the target:                                                     in the metallic mode: -668 V                                                  in the working point between                                                                        -340 V                                                  metallic mode and oxidic mode:                                                coating:              SiO.sub.2                                               index of refraction SiO.sub.2                                                                       1.47                                                    at λ = 633 nm:                                                         extinction coefficient k of SiO.sub.2                                                               <1E-5                                                   at θ = 633 nm:                                                      2)  apparatus:            BAK 760 of the firm                                                           Balzers AG, Balzers/FL                                  cathode:              AK 525 of the firm                                                            Balzers AG                                              magnet system:        MA 525 of the firm                                                            Balzers AG                                              target:               S10-3976 silicon target                                                       (5 × 25 inches)                                   DC power supply:      10 kW                                                   distance between target and substrate:                                                              60 mm                                                   rotational frequency of workpiece carrier:                                                          0.5 Hz                                                  repetition frequency (repetition rate)                                                              17 μsec                                              of inventively applied discharge:                                             time-span of discharge                                                                              16 μsec                                              discharge conditions: short circuit                                           sputtering power:     2 kW                                                    gas pressures in the recipient:                                               Ar:                   pAr = 8E - 4 bar                                        O.sub.2 :             pO.sub.2 = 2E - 5 mbar                                  DC voltage at the target                                                                            -660 v                                                  in the metallic mode:                                                         in the working point between                                                                        -550 v                                                  metallic and oxidic mode:                                                     deposited layer:      284 nm SiO2                                             energy yield:         DDR(SiO2) =                                                                   44.6 nm mm 2/Ws                                         (DDR = deposited volume of coating                                            per energy applied therefor)                                                  index of refraction of the SiO2                                                                     1.47                                                    at λ = 633 nm                                                          extinction coefficient k for the SiO2                                                               <1E-5                                                   at λ = 633 nm                                                      ______________________________________                                    

Examples for Inventive Ionplating

1. Forming tools were coated in a reactive ionplating process with anapparatus construed as schematically shown in FIG. 12a and according tothe embodiments according to the FIGS. 15 and 18. Silicon was evaporatedand the tools coated with a silicon nitride coating. The forming toolsthus coated with a corrosion resistant layer were afterwards coated witha further hard material coating to make the tools wear resistant.

Therefore, titanium-carbonitride was used for aluminum flanching wheelsas forming tools, titanium-nitride for injection mould forms forpolyvinylchloride and chromium-nitride coating for metal pressure diecasting tools.

Thereby, first, well-known prior art ionplating processes were used.

Only with the implementation of the inventive method to form aninventive ion plating apparatus, i.e. applying a DC voltage anddischarging at a predetermined repetition rate, problems were resolvedwhich resulted from the electrically isolated bottom layer (isolatingcovering) and, especially, a sufficiently adhering abrasion resistantcoating could be deposited on the silicon-nitride layer. Only the toolswhich had been treated by inventive ionplating could be used inpractice.

2. It was attempted to coat turn-over cutting plates by known physicalvapor deposition procedures (PVD). Thereby, simultaneously aluminum andchromium were evaporated from crucible. Thereby it was recognized thatcoating layers are on one hand of sufficient hardness, but that theabrasion resistance does not suffice for applications with speciallyhigh demands with respect to abrasion.

An analysis of the coating with the raster electron microscope showedthat the layers were not sufficiently compact.

Therefore, the same coating was deposited by the inventive ion platingmethod, whereby and as desired a significant increase of the abrasionresistance was achieved at the turn-over cutting plates.

For mass production according to the two examples given above with morethan two workpiece carriers, the apparatus was construed asschematically shown in FIG. 18. It was recognized that a minimaltimespan of lOnsec between discharge timespans applied at the differentworkpiece carriers was necessary. The operation became especially stablewith such time intervals larger than 200 nsec between respectivedischarge timespans at the different workpiece carriers.

With this method workpieces deposited on a large number of workpiececarrier surfaces could be treated "quasi simultaneously" by inventiveionplating. The apparatus used comprised twelve different workpiececarriers. Thereby, when the turn-over cutting plates were coated, theirabrasion resistance became substantially equal to the abrasionresistance of such turn-over cutting plates which had been coated byprior art high temperature CVD methods.

Generally spoken, workpieces which have been inventively ion plated,have a higher ductility than workpieces which have been treated by hightemperature CVD methods. This because the inventive ion plating leads tosignificant lower temperatures during the treating process. The saidhigh ductility which was achieved by the inventively ionplated turn-overcutting plates, allows such cutting plates to be used in uninterruptedcutting operation.

The following additional and substantial advantages of the inventionwere recognized:

1. For cathode sputtering:

Besides the advantages which have been already mentioned, that

the efficiency of the inventive method and apparatus in the sense ofdeposited coating volume per applied electrical energy is risen comparedwith previously known methods,

the transition from the metallic mode in the reactive or oxidic modebecomes steadier so that a process working point is easier to stabilizeby negative feedback control measures in the said transition mode.

2. For inventive ionplating:

Besides the advantages mentioned above the following advantages wererecognized, namely that

the adherence of inventively ion plated coatings is significantlyimproved,

the compactness of inventively deposited coatings is significantlyincreased and thereby the abrasion resistance,

the treatment temperature of the workpieces to be treated mayinventively be significantly lowered as is known for ionplating. By thefact that ionplating may now be applied due to its inventive improvementthere, where up to now it was customary to apply high temperature CVDmethods, the ductility of inventively treated workpieces maysignificantly be increased compared with workpieces equally coated, butby high temperature CVD.

Subsequently and in the form of a sequence of summarizing statements,the most important features and feature combinations of the inventionare listed:

The invention considers:

I. A method for treating workpieces in a vauum atmosphere by whichmethod an electrical signal is applied to at least two electroconductivesurfaces, which surfaces are exposed to a vacuum treatment atmosphereand whereby at least one of said two surfaces has a "isolating covering"of not or low conductive material which at least in part covers saidsurface and whereby the vacuum atmosphere comprises electricalchargecarriers and whereby further the output signal of a DC signalgenerator is applied to the oneport formed by said two electroconductivesurfaces, and wherin further, during the treatment, there is applied afurther electrical signal which is different from the output signal ofsaid generator to said oneport at a repetition rate and during timespansof such extent as required by electric charges depositing in the vacuumatmosphere and on said isolating covering and whereby, further, duringsaid treatment the output signal of the DC signal generator is appliedconsiderably longer than the further electric signal is applied.

II. A method for workpiece treatment in a vacuum atmosphere whichcomprises electrical chargecarriers and whereby at least twoelectroconductive surfaces are interact with the vacuum atmosphere andat least one thereof is covered at least in part by an isolatingcovering of not or low conductive material, and whereby the saidelectroconductive surfaces are at least for short time intervals atpredetermined or at adjustable repetition rate shortened and/or areconnected to a source of electrical charge via a discharge or chargeexchange current path.

III. A method following a method with the features of I and II, wherebyfurther short circuiting and/or applying a source of electrical chargeis performed in timespans during which said further electrical signal isapplied and whereby at least the isolating covering surface according to(I) forms that one according to (II).

IV. A method preferably realized according to the features of I or III,whereby the further signal is generated by choppering of the outputsignal of the generator.

V. A method preferably realized according to the features of IV, wherebythe further signal is generated by parallel choppering of the outputsignal of the generator.

VI. A method preferably following one of the sets of features I to V, atwhich the at least one workpiece

a) comprises a surface of not or low conductive material as saidisolating covering and/or

b) is coated with a layer of not or low conductive material as saidisolating covering by said treatment and the workpiece is deposited onone of said electroconductive surfaces.

VII. A method preferably following the set of features according to VI,whereby on a surface which is formed of not or low conductive materialas the said isolating covering, a layer of conductive material isdeposited by the treatment process.

VIII. A method wherein preferably the set of features of one of the setsI to VII is applied and whereby the workpiece treatment is an ionplatingprocess.

IX. A method which preferably follows the features of one of the sets Ito VIII, whereby further

a) a conductive material, whereon the said isolating covering isprovided independent from the treatment process or is applied during thetreatment process, is evaporated or sputtered as source material for thetreatment process and/or

b) a not or low conductive material as a source material, which formsthe said isolating covering, is evaporated for the treatment process and

the material forms one of said surfaces or is deposited on a conductiveone of the said surfaces.

X. A method preferably following one of the sets defined in I to IX,whereby the treatment process is a PVD treatment process or a reactivePVD treatment process or a plasma enhanced CVD treatment process.

XI. A method preferably following the features of one of the sets I toX, whereby further a plasma is generated in the vacuum atmosphere.

XII. A method preferably following the set of features according to IX,whereby further the plasma is fed from one of the said surfaces.

XIII. A method preferably following the set defined in XI, wherebyfurther one of the electrodes from which the plasma discharge is fed, isdeposited on the electric potential of one of the said surfaces.

XIV. A method preferably following one of the sets II to XIII, wherebyfurther the discharge or charge exchange behaviour is measured in thecurrent path.

XV. A method preferably following the set defined in XIV, wherebyfurther the thickness of an isolating covering is retrieved from themeasured discharge or charge exchange behaviour.

XVI. A method preferably following the set of features as defined inXIV, whereby the actual occupation of the isolating covering byelectrical chargecarriers is retrieved from the measured discharge orcharge exchange behaviour.

XVII. A method which preferably follows one of the sets of featuresaccording to II to XVI, whereby the growth of an occupation withelectrical chargecarriers on the isolating covering is measured.

XVIII. A method preferably following a set of features according to XIVto XVII, whereby further the measured discharge or charge exchangebehaviour is compared with a rated behaviour and, as a function of theresult of this comparison, the covering with electrical chargecarriersof the isolating covering is adjusted by external feeding electricalcharges and/or by adjusting the repetition frequency of discharge orcharge exchange cycles and/or by adjusting the time extent provided foreach discharge or charge exchange step, so that the resultant measuredactual discharge or charge exchange characteristic substantially accordsto the rated behaviour.

XIX. A method preferably following the features of one of the sets XIVto XVIII, whereby spontaneous break-throughs or flash-overs, generallycalled "arcing", caused by occupation of said isolating covering byelectrical chargecarriers, is monitored or watched and, according totheir frequency of occurrence and/or their kind of occurrence theoccupation by electrical chargecarriers is open loop adjusted or isnegative feedback controlled by varying an electrical charge externallyinput and/or by varying the repetition rate of discharge or chargeexchange cycles and/or by adjusting the time extent of discharge orcharge exchange cycles, so that a desired behaviour with respect to thesaid spontaneous arcing is reached.

XX. A method preferably following the features of one of the sets XIV toXIX, whereby then, when the measured discharge or charge exchangebehaviour at least substantially accords with a predetermined behaviour,the respective discharge or charge exchange cycle is stopped.

XXI. A method preferably following a set of features according to one ofII to XX, whereby in timespans between discharge or charge exchangecycles a growth of said occupation with electrical chargecarriers iscontrolled by external input of electrical charge onto that surface withthe isolating covering, thus being the surface carrying the electricalchargecarriers deposited on-said isolating covering.

XXII. A method preferably following the set of features according toXXI, whereby further the growth of occupation with electricchargecarriers is controlled as growth of a desired layer on at leastone workpiece during ionplating deposition of said layer.

XXIII. A method which preferably follows one of the sets of featuresaccording to I to XXII, whereby the workpiece surface acting itself asisolating covering is not or low conductive and is coated by ionplatingand/or the workpiece surface is coated by ionplating with a coating ofnot or low conductive material as an isolating covering, and thereby aworkpiece carrier surface is one of said electroconductive surfaces,whereby a capacitive element is connected in series to the said carriersurface in the discharge current path, so that during time intervals ofionplating this capacitance and the capacitance formed by the at leastone isolating covering at the workpiece appears connected in series andduring time intervals of discharge or charge exchange appear connectedin parallel, and that during plating time intervals this seriesconnection is electrically charged so that there occurs an at leastpredominantly pre-set ion occupation on said workpieces.

XXIV. A method which preferably follows the set of features according toXXIII, whereby in time intervals of ionplating a predetermined oradjustable electric charge is fed through the series connection of thesaid two capacitors and that therewith the occupation with electricalchargecarriers at the workpiece surface is controlled.

XXV. A method which preferably follows the set of features according toXXIV, whereby the said electrical charge is applied by applying avoltage with predetermined time derivative to the said series connectionof the two capacitors.

XXVI. A method preferably following the set of features according toXXIII to XXV, further comprising electrically charging said seriesconnection with inductively generated over-voltage.

XXVII. A method which preferably follows the set of features as definedin one of XXIII to XXVI, whereby charging said series connection in timeintervals of ionplating occurs with a voltage signal having aramp-shaped time course and thus with an at least substantially constantelectrical current, and that thereby there is realized a substantiallyconstant rate of electric chargecarriers deposition.

XXVIII. A method following preferably a set of features according to oneof I to XXVII, whereby further two or more than two pairs of surfacesare provided and each pair or each group of such pairs is provided witha DC signal generator and/or with a discharge or charge exchange currentpath, each pair or groups is operated mutually staggered in time.

XXIX. A method which preferably follows a set of features according toone of I to XXVIII, whereby workpieces are provided on at least twopairs or groups of said surfaces and are treated by ionplating, and thatfurther the pairs or groups of pairs are subjected in time staggeredmanner to discharge cycles.

XXX. A method which preferably follows one of the sets of featuresaccording to XXIII to XXIX, whereby the discharge behaviour is measured,the measuring result is compared with a rated behaviour and by varyingcharging the said series connection during time intervals of ionplatingas a function of the result of said comparison, the occupation by ionsof the workpiece and thus the measured discharge behaviour is adjustedto substantially become equal to the rated behaviour, thereby possiblyconsidering time-variations of the capacitor formed by said one surface,thereon the isolating covering and thereon the occupation by electricalchargecarriers, by considering variations of the discharge timeconstant.

XXXI. A method which preferably follows a set of features according toone of XXIII to XXX, whereby further the discharge cycle is repeatedwith a repetition rate or frequency of between 50 kHz and 500 kHz(bothincluded), preferably with at least 90 kHz and even more preferably withat least 100 kHz.

XXXII. A method preferably following the set of features according toone of the sets XXIII to XXXI, whereby on at least one workpiece thereis deposited at least one corrosion resistant and/or at least one wearresistant coating by ionplating, so e.g. a not or low conductive firstlayer as a corrosion resistant layer and an electroconductive secondlayer as wear resistant layer or further combinations of layers as asystem of layers with two and more than two layers.

XXXIII. A method which preferably follows the features according to oneof the sets I to XXI, whereby an electroconductive material is sputteredby means of a plasma discharge in the vacuum atmosphere, which plasmadischarge is sustained between the material to be sputtered and acounterelectrode, and whereby the sputtered material is reacted in thevacuum atmosphere with an inlet reactive gas to form a not or lowconductive material compound, and further a controlled discharge currentpath is provided across the plasma discharge stage and that there isprovided across said discharge current path the DC signal generator andan interrupting switch unit, both connected in series, whereby theinterrupting switch unit and the controlled discharge current path areclosed in phase opposition.

XXXIV. A method preferably following a set of features as defined inXXXIII, whereby further, especially when the said DC signal generatorhas an output characteristic substantially according to a currentsource, the said interrupting switching unit is bridged by an electroniccircuit, preferably made of passive elements, preferably made ofresistances.

XXXV. A method which preferably follows a set of features as defined inXXXIII or XXXIV, whereby further the reactive sputtering process isoperated in the oxidic or in the transition mode between metallic andoxidic operation mode.

XXXVI. A method which preferably follows the features as defined in oneof the sets XXXIII to XXXV, whereby further silicon is sputtered and isreacted with oxygen for depositing a silicon oxide layer.

XXXVII. A method which preferably follows the features according to oneof the sets XXXIII to XXXVI, whereby dielectric or low orsemi-conductive layers are formed from material based on a metal.

XXXVIII. A method which preferably follows the features as defined inthe sets I to XXI, XXXIII to XXXVII, whereby the further electric signalis applied intermittently and with a repetition rate according to afrequency of 50Hz to 1 MHz (both limits included), preferably of 5kHz to100 kHz (both limits included), further preferred especially of 10 kHzto 20 kHz (both limits included).

XXXIX. A method which preferably follows features according to one ofthe sets I to XXXVIII whereby the said further electric signal isintermittently applied during time spans with extents of between 50nsecand 10 μsec (both limits included) preferably of between 0,5 μsec and 2μsec (both limits included) or of 2 μsec and 10 μsec (both limitsincluded).

XL. A method for controlling the occupation with electricalchargecarriers of a surface of an object which surface is formed by anot or low conductive part of said object or by a not or low conductivecovering of said object, whereby said object is deposited adjacent or onan electro-conductive surface and whereby the surface of said object isexposed to a vacuum atmosphere with electrical chargecarriers whereby afurther electro-conductive surface is provided exposed to said vacuumatmosphere and a electrical charge is driven through said oneelectro-conductive surface, the said object with said surface, a regionof said vacuum atmosphere and said further electro-conductive surface ina controlled manner whereby preferably a plasma-discharge is generatedin said vacuum atmosphere.

XXXXI. A vacuum treatment apparatus with a vacuum recipient (3) thereina carrier arrangement for workpieces at which apparatus an electricsignal generator is connected to at least (2a, 2b) electro-conductivesurfaces which interact with said atmosphere in the vacuum recipientwhereby the signal generator comprises a DC-signal generator (8) and aunit (12, 14, 14s, S₁) at the output side of the DC-signal generator bywhich unit the output signal of the generator (8) is controllably variedto generate an electric signal applied to said two electro-conductivesurfaces (2a, 2b) whereby the said unit is so controlled or is socontrollable (16, 160) that with a predetermined or adjustablerepetition frequency and/or for predetermined or adjustable time-spansthe signal applied to the said two surfaces is different from the outputsignal of the said DC-signal generator (8).

XXXXII. A vacuum treatment apparatus with a vacuum recipient (3) andtherein a carrier arrangement for workpieces further with means forgenerating-electrical chargecarriers in said recipient whereby twoelectro-conductive surfaces (2a, 2b) are in interaction with theatmosphere in the recipient (3) and are interconnected via acontrollable discharge or charge exchange current path (14, 14s, S₁).

XXXXIII. A vacuum-treatment apparatus which preferably has the featureof the sets XXXXI and XXXXII whereby further the repetition rate and thecontrol of said discharge or charge exchange current path aresynchronized and at least one of the electro-conductive surfacesaccording to the apparatus as defined in XXXXI is that of the apparatusdefined in the features of XXXXII.

XXXXIV. A vacuum-treatment apparatus which has preferably the featuresas defined in one of the sets XXXXI to XXXXIII whereby further the twoelectro-conductive surfaces (2a, 2b) are interconnected via a controlledshort-circuiting unit (14s, S₁)

XXXXV. A vacuum-treatment apparatus which preferably has features asdefined for the apparatus according to XXXXIV whereby theshort-circuiting switching unit (S₁) acts as well as the unit at theoutputside of said DC-signal generator (8) and as a control unit (14) inthe discharge or charge exchange current path.

XXXXVI. A vacuum apparatus which preferably has the features of theapparatus according to one of the apparatus as defined in XXXXI to XXXXVwhereby further one of the electro-conductive surfaces (29) forms aworkpiece carrier surface or forms a surface (52, 2b) for supporting asource-material which source-material is used during a coating processat said apparatus of at least one workpiece (1).

XXXXVII. A vacuum apparatus which preferably has the features of anapparatus according to one of XXXXI to XXXXVI whereby one of theelectro-conductive surfaces (2a) forms a workpiece carrier surface andthe apparatus is a ionplating apparatus.

IIL. A vacuum treatment apparatus which preferably has the features ofan apparatus as defined in one of the sets XXXXI to XXXXVI wherebyfurther a target object (64) is provided which is sputtered and whereinone of said electro-conductive surfaces (2b) is contacting said vacuumatmosphere via the said target object (64).

IL. A vacuum treatment apparatus which has preferably the feature of theapparatus according to IIL whereby the target object is part of amagnetron arrangement.

L. A vacuum treatment apparatus which has preferably the features of theapparatus according to one of the sets XXXI to IL whereby means (52, 50,3, 64) are provided to generate a plasma-discharge (PL) in therecipient.

LI. A vacuum treatment apparatus which preferably has the features of anapparatus as defined in one of the sets XXXI to L whereby at least oneelectrode-pair is provided to generate a plasma-discharge in therecipient and whereby preferably at least one of these electrodes (64)forms one of the said electro-conductive surfaces (2b).

LII. A vacuum treatment apparatus which has preferably the features ofan apparatus as defined in one of the sets XXXXI to LI whereby furtherat least three (2a, 2a₂, 2b) of the said electro-conductive surfaces areprovided and grouped at least in pairs and at least one generator (8)according to set XXXXI and/or a current path according to set XXXXII isprovided to each group and relatively, controlled by means of atime-control-unit (70) staggered in time.

LIII. A vacuum treatment apparatus which has preferably the features ofan apparatus as defined by the features of set LII whereby further morethan two groups of electro-conductive surfaces are controlled inmutually time staggered manner by the time control unit.

LIV. A vacuum treatment apparatus which has preferably the features ofan apparatus as defined in one of the sets XXXXI to LII whereby furthera gasfeed arrangement (18) is provided in the vacuum recipient whichgasfeed arrangement is linked to a reactive gas tank.

LV. A vacuum treatment apparatus which preferably has the features of anapparatus as defined by the features of one of the sets XXXXI to LIVwhereby the apparatus is a PVD-apparatus or a reactive PVD-apparatus oran apparatus for plasma-enhanced CVD or an apparatus for thermical CVDwith an arrangement for ionizing of a gasious part of said vacuumatmosphere in the recipient.

LVI. A vacuum treatment apparatus which has preferably the features ofan apparatus defined by the features of one of the sets XXXXI to LVwhereby further a low voltage glow discharge-stage is providedpreferably with a glow electron-emitting cathode (50).

LVII. A vacuum treatment apparatus which has preferably the features ofan apparatus as defined by one of the sets of features XXXXI to LVIwhereby at least two electrodes (60a, 60b) are provided for generating aplasma (PL) in the vacuum recipient (3) and whereby at least one ofthese electrodes (60b) is connected to the electrical potential of oneof the said electro-conductive surfaces (62).

LVIII. A vacuum treatment apparatus which preferably has the features ofan apparatus as defined by one of the sets of features XXXXI to LVIIwhereby the controlled discharge or charge exchange current path iscapacitive (C_(I), C_(D), C_(D1)) when this path is controllably closed.

LIX. A vacuum treatment apparatus which has preferably the features ofan apparatus as defined by one of the sets XXXXI to LVIII whereby anelectrical charge storage (C_(D), 20, C_(D1)) is provided in thedischarge current path and/or a voltage source (U_(E)).

LX. A vacuum treatment apparatus which has preferably the features of anapparatus as defined in one of the sets XXXXI to LIX whereby further ameasuring arrangement (24, 32, 66) is provided along for measuring asignal representative for a current flowing through said controlleddischarge or charge exchange current path.

LXI. A vacuum treatment apparatus which has preferably the featuresaccording to an apparatus as defined in set LX whereby the output signalof the measuring arrangement acts on an adjusting means (30, 16, 160,56, 73) for controlling said control-discharge or charge-exchangecurrent path.

LXII. A vacuum treatment apparatus which has preferably the features ofan apparatus as defined in one of the sets LX or LXI whereby the outputof the measuring arrangement acts on a threshold sensitive unit (26)with preferably adjustable threshold value (W) the output thereof beingled to a control input (30, R) for said control discharge or chargeexchange current path.

LXIII. A vacuum treatment apparatus which has preferably the features ofan apparatus as defined by at least one of the sets LX to LXII wherebyfurther the output of the measuring arrangement possibly via an analogueto digital converter (34) acts on an actual value storage means (36) theoutput of which being led to one input of a comparison unit (38) as wellas the output of a rated value storage means (40) and that the output ofthe comparison unit (38) acts on a control input of said controlleddischarge or charge exchange current path.

LXIV. A vacuum treatment apparatus which has preferably the features ofan apparatus as defined according to one of the sets XXXXI to LXIIIwhereby a controlled or controllable source of electric charge (20, 22,44, 58, C_(D1)) is provided on an electric path between the said twoelectro-conductive surfaces (2a, 2b) especially during time-spans inwhich the said controlled discharge or charge-exchange current path iscontrollably interrupted or controlled to become high-ohmic.

LXV. A vacuum treatment apparatus which preferably has a feature of anapparatus as defined by one of the sets XXXXI to LXIV whereby further acapacitive element (C_(D1)) is connected to at least one of the saidelectro-conductive surfaces (2a, 2b) in said current path and furthercomprising means (46,46a, 58) for electrically charging the serialconnection of said capacitive element (D_(D1)) with the oneport formedbetween said two electro-conductive surfaces (2a, 2b) whereby saidcapacitive element appears in electrical parallelism to said oneportwhen said current path is controllably closed.

LXVI. A vacuum treatment apparatus which comprises preferably thefeatures of an apparatus as defined in one of the sets of features XXXXIto LXV whereby a capacitive element (C_(D1)) is electrically connectedto at least one of the electro-conductive surfaces (2a) and that whenthe said current flow path is controlled to be high-ohmic or interruptedthe oneport defined between the two electro-conductive surfaces (2a, 2b)is connected in series with the said capacitive element and a voltagesource (58) is as well in series thereto which source generates anoutput signal controllably varying in time or adjustably varying in time(dU/dt) so that by the said serial connection and as a function of thevariation of said output signal of said voltage source in time thereflows through said serial connection a controlled or adjustable current.

LXVII. A vacuum treatment apparatus preferably with the features of anapparatus as defined in one of the sets, of features LXV to LXVI wherebymeans are provided to charge said serial circuit which compriseinductive means (L₆₆).

LXVIII. A vacuum treatment apparatus preferably with the features of anapparatus as defined in at least one of the sets of features XXXXI toLXVI whereby the apparatus is an ionplating apparatus and one of thesaid electro-conductive surfaces (2a) forms the carrier for workpieces(1) and whereby via a capacitive element (C_(D1)) and a controlswitching unit (S₁) a discharge current path is formed between the saidconductive surfaces (2a, 2b) and the DC signal generator (8) isconnected in parallel to said switching unit (S₁) and whereby preferablya source of electric charge (58, D_(D1)) acts in series to saidswitching unit (S₁) and said capacitive element (C_(D1)) or that acharge source comprises said capacitive element (C_(D1)) wherebyoperation of said source of electric charge is synchronized with theoperation of said switching unit (S₁) so that when said switching unit(S₁) is open a predetermined or adjustable charging current is generatedto and from said electro-conductive surfaces (2a, 2b).

LXIX. A vacuum treatment apparatus preferably comprising the features ofan apparatus as defined in the set of features LXVIII whereby more thanone, preferably more than two of the electro-conductive surfaces(2a_(x)) acting as workpiece carriers are provided and wherein,respectively, a switching unit is provided to each of saidelectro-conductive surfaces acting as workpiece carriers to form,respectively, a discharge current path and therein a capacitive element(C_(D1)) and, preferably, a source of electric charge (58, C_(D1)) or asource of electric charge is formed with said capacitive elements(C_(D1)) whereby a time control unit (162, 71) is provided whichoperates the switching units (S₁) in a mutually time staggered manner.

LXX. A vacuum treatment apparatus preferably construed with the featuresof an apparatus as defined by one of the sets of features XXXXI to LXIXwhereby there is provided in the recipient a sputtered target object(64) at which there is provided one of the said electro-conductivesurfaces (2b) whereby the two electro-conductive surfaces (2a, 2b) arelinked by a controlled switching unit (S₁) to form a control dischargecurrent path and further a DC-signal generator (8) is provided with aswitching unit (S₂), in series to its output whereby the switching units(S₁, S₂) are intermittently operated under the control of a time controlunit (160) in phase opposition.

LXXI. A vacuum treatment apparatus preferably construed with thefeatures of an apparatus as defined by the set of features LXX wherebydetection means are provided to detect arcing so e.g. flash-overs andbreak-throughs within the recipient (3) and that the output signal orsaid detection means acts on a first input of a comparator unit (70),the output signal of a rated value generating unit (72) being led to asecond input of said comparison unit, the output signal of saidcomparison unit (70) acting on an adjusting unit and preferably on acontrol input of a time control unit (16, 160) which latter adjusts theintermittent operation of the switching unit (S₁).

LXXII. A vacuum treatment apparatus preferably with the features of anapparatus as defined in at least one of the sets of features XXXXI toLXXI the apparatus being an apparatus for producing optical layers onworkpieces.

LXXIII. An apparatus preferably construed with features of an apparatusas defined by the sets of features LXXII whereby the apparatus comprisesat least one sputtered target object (64).

LXXIV. A vacuum treatment apparatus which preferably comprises thefeatures of an apparatus as defined in one of the sets of features XXXXIto LXXI the apparatus being an apparatus for the production of hardmaterial and/or wearprotective coatings.

LXXV. A vacuum treatment apparatus which is preferably construed withthe features of an apparatus as defined by the set of features LXXIVwhereby the apparatus is an ionplating apparatus.

We claim:
 1. A vacuum treatment apparatus, comprising:a vacuum recipientfor containing an atmosphere; means for generating electrical chargecarriers in the atmosphere within said recipient, the electrical chargecarriers being of the type that form electrically insulating material; awork piece carrier arrangement in said recipient; at least twoelectroconductive surfaces in said recipient; a controlled adjustingunit with a time controlled discharge or charge current loopoperationally bridging said ekectricibdyctuve syrfaces and having a highohmic resistance during first time spans and a lower ohmic resistanceduring second time spans, so that a voltage between saidelectroconductive surfaces, due to electrical charge carriers in saidatmosphere, may be discharged through said current loop during saidsecond time spans, and with a timing unit connected to a timing input ofsaid time controlled current loop for controlling said first and secondtime spans to occur repetitively so as to prevent arcing at parts ofsaid electroconductive surfaces which are or which are becomingelectrically isolated from said atmosphere by some of said electricalcharge carriers depositing as insulating material thereon.
 2. Theapparatus of claim 1, wherein said controlled adjusting unit comprises acontrolled switching unit intermittently short-circuiting said twoelectroconductive surfaces.
 3. The apparatus of claim 1, wherein one ofsaid two electroconductive surfaces is one: of a workpiece carriersurface; and a surface for delivering material for coating workpiecesinto said atmosphere.
 4. The apparatus of claim 1, wherein one of theelectroconductive surfaces is a workpiece carrier surface and theapparatus is an ion-plating apparatus.
 5. The apparatus of claim 1,further comprising means for generating a plasma discharge within saidrecipient.
 6. The apparatus of claim 1, wherein the at least twoelectroconductive surfaces comprise at least three electroconductivesurfaces, the at least three electroconductive surfaces taken two at atime forming three pairs of electroconductive surfaces and wherein atleast two adjusting units are provided and are respectivelv connected totwo of said three pairs of electroconductive surfaces and furthercomprising a time sequence control unit for controlling said at leasttwo adjusting units to generate said second time spans to be staggeredin time.
 7. The apparatus of claim 1, further comprising a gas feedarrangement with an outlet arrangement in said vacuum recipient, atleast a part of said gas feed arrangement being linked to a tankcontaining a reactive gas.
 8. The apparatus of claim 1, furthercomprising at least two plasma generating electrodes in said recipient,one of said electrodes being connected to an electrical potential whichis the same as an electrical potential connected to one of saidelectroconductive surfaces.
 9. The apparatus of claim 1, wherein saidadjusting unit comprises at least one of a capacitor means and of avoltage source.
 10. The apparatus of claim 1, further comprisingmeasuring means for measuring an electric current flowing between saidelectroconductive surfaces to generate an output signal.
 11. Theapparatus of claim 10, wherein the output signal of said measuring meansis fed back to the timing unit for adjusting said first and second timespans.
 12. The apparatus of claim 11, wherein the output of saidmeasuring means is led to an input of a threshold-sensitive unit, theoutput of the threshold-sensitive unit acting on a control input foradjusting said time spans.
 13. The apparatus of claim 1, wherein saidadjusting unit comprises a source of electric charge.
 14. The apparatusof claim 13, wherein said adjusting unit comprising a controlled currentpath connecting said electroconductive surfaces, said source of electriccharge feeding electric charge to electroconductive surfaces during saidsecond time spans.
 15. The apparatus of claim 1, further comprising acontrolled current path between said electroconductive surfaces, saidcurrent path comprising a capacitative element.
 16. The apparatus ofclaim 1, wherein said adjusting unit comprises a capacitative elementconnected to one of said electroconductive surfaces, a voltage sourceand a switching unit switching said voltage source in series to saidcapacitative element and between said two electroconductive surfaces.17. The apparatus of claim 16, wherein said voltage source generates anoutput signal which varies in time in a determined or in an adjustablemanner so that said voltage source drives a controlled or adjustablecurrent to said electroconductive surfaces.
 18. The apparatus of claim1, wherein said first time span is substantially longer than said secondtime span.
 19. The apparatus of claim 1, further comprising a detectionunit for detecting arcing within said vacuum recipient, said detectionunit having an output connected to said controlled adjusting unit forcontrolling said controlled adjusting unit.
 20. A vacuum treatmentapparatus, comprisinga vacuum recipient for containing a vacuumatmosphere; means for generating electrical charge carriers in saidatmosphere, the electrical charge carriers being of the type that formelectrically insulating mateal a workpiece carrier arrangement in saidrecipient; at least two electroconductive surfaces in said recipient andexposed to said atmosphere; a generator unit having an output connectedto said electroconductive surfaces and comprising: a DC generator withan output and generating a DC output signal; a controlled adjusting unitwith an input connected to the output of said DC generator and with anoutput connected to said output of said generator unit; said controlledadjusting unit comprising a time-controlled discharge or charge currentloop bridging said electroconductive surfaces and said DC generator,said discharge or charge current loop being controllably switchable tohave a higher ohmic resistance during first time spans and a lower ohmicresistance during second time spans, and further comprising a timingunit connected to a timing input of said controlled current loop andcontrolling said first and second time spans to occur repetitively so asto prevent arcing at parts of said electroconductive surfaces which areor which are becoming electrically isolated from said atmosphere by someof said electrical charge carriers depositing as insulating materialthereon.
 21. The apparatus of claim 20, further comprising a detectionunit for detecting arcing within said vacuum recipient, said detectionunit having an output connected to said controlled adjusting unit forcontrolling said controlled adjusting unit.
 22. The apparatus of claim20, wherein said first time span is substantially longer than saidsecond time span.
 23. The apparatus of claim 20, wherein said controlledadjusting unit comprises a controlled switching unit intermittentlyshort-circuiting said two electroconductive surfaces.
 24. The apparatusof claims 20, wherein one of said two electroconductive surfaces is one:of a workpiece carrier surface; and a surface for delivering materialfor coating workpieces into said atmosphere.
 25. The apparatus of claims20, wherein one of the electroconductive surfaces is a workpiece carriersurface and the apparatus is an ion-plating apparatus.
 26. The apparatusof claim 20, further comprising means for generating a plasma dischargewithin said recipient.
 27. The apparatus of claim 20, where the at leasttwo electroconductive surfaces comprise at least three electroconductivesurfaces, the at least threE electroconductive surfaces being taken twoat a time to form three pairs of electroconductive surfaces and whereinat least two adjusting units are provided and are respectively connectedto two of said three pairs of electroconductive surfaces, and furthercomprising a time sequence control unit for controlling said at leasttwo adjusting units to generate said second time spans to be staggeredin time.
 28. The apparatus of claim 20, further comprising a gas feedarrangement with an outlet arrangement in said vacuum recipient, atleast a part of said gas feed arrangement being linked to a tankcontaining a reactive gas.
 29. The apparatus of claim 20, furthercomprising at least two plasma generating electrodes in said recipient,one of said electrodes being connected to an electrical potential whichis the same as an electrical potential connected to one of saidelectroconductive surfaces.
 30. The apparatus of claim 20, wherein saidadjusting unit comprises at least one of a capacitor means and of avoltage source.
 31. The apparatus of claim 20, further comprisingmeasuring means for measuring an electric current flowing between saidelectroconductive surfaces to generate an output signal.
 32. Theapparatus of claim 31, wherein the output signal of said measuring meansis fed back to the timing unit for adjusting said first and second timespans.
 33. The apparatus of claim 32, wherein the output of saidmeasuring means is led to an input of a threshold-sensitive unit, theoutput of the threshold-sensitive unit acting on a control input foradjusting said time spans.
 34. The apparatus of claim 20, wherein saidadjusting unit comprises a source of electric charge.
 35. The apparatusof claim 34, wherein said adjusting unit comprises a controlled currentpath connecting said electroconductive surfaces, said source of electriccharge feeding electric charge to electroconductive surfaces during saidsecond time spans.
 36. The apparatus of claims 20, further comprising acontrolled current path between said electroconductive surfaces, saidcurrent path comprising a capacitative element.
 37. The apparatus ofclaim 20, wherein said adjusting unit comprises a capacitative elementconnected to one of said electroconductive surfaces, a voltage sourceand a switching unit switching said voltage source in series to saidcapacitative element and between said two electroconductive surfaces.38. The apparatus of claim 37, wherein said voltage source generates anoutput signal which varies in time in a determined or in an adjustablemanner so that said voltage source drives a controlled or adjustablecurrent to said electro conductive surfaces.